Adriatic League

At various points throughout mid-to-late 1990s, in the years following the breakup of SFR Yugoslavia and ensuing Yugoslav Wars, different basketball administrators from the newly independent Balkan states floated and informally discussed the idea of re-assembling a joint basketball competition to fill the void left by the dissolution of the former Yugoslav Basketball League whose last season was 1991–92.

However, no concrete action towards that end was taken before the summer 2000 ULEB-supported creation of Euroleague Basketball Company under the leadership of Jordi Bertomeu that immediately confronted FIBA Europe, then proceeded to take a handful of top European clubs into its new competition for the 2000–01 season thereby opening an organizational split in European club basketball. During the 2000–01 split in the continent's top club competition, local Balkan basketball administrators from the ULEB-affiliated clubs Cibona, Olimpija, and Budućnost (that already competed in this new 'breakaway' Euroleague competition) shifted the discussions of creating a regional Balkan-wide basketball league into higher gear.^[]

On the public relations front, Adriatic League was met with strong and mixed reactions. Though many hailed it as an important step for the development of club basketball in the Balkans region, many others felt that it brings no new quality and that it's not worth dismantling three domestic leagues. There was a lot of negative reaction from political circles, especially in Croatia, with even TV panel discussions being broadcast on Croatian state television. A very vociferous opinion in the country saw the league's formation as a political attempt to reinstate Yugoslavia. The league organizers for their part did their best to appease the Croatian public with statements such as the one delivered by Radovan Lorbek in Slobodna Dalmacija in September 2001:

This is not a Yugoslav league, and it will never become a Yugoslav league. The Adriatic League has no clubs from Serbia and Macedonia, therefore the Adriatic League and Yugoslav league are not the same thing.

Ten years later, in a 2011 interview for the Serbian newspaper Press, Roman Lisac explained the league's behind the scenes strategy during its nascent stages was actually quite different:

I'm convinced the league would've never been able to survive without Serbian clubs. Getting Crvena zvezda and Partizan to join the league was something that we worked on from day one. However, the situation ten years ago was not that simple. Too much antagonistic post-war politics was still all around us, and it made our task all the more difficult. Everything that smelled of old Yugoslavia caused a lot of resistance both in Croatia and in Serbia. I repeat, the idea of having both Crvena zvezda and Partizan in the league was there from the very beginning, but we avoided talking about it publicly because of politics.

The league is still occasionally criticized by observers around European basketball for reducing the scope and calendar of the domestic competitions that it replaced for the region's more-established clubs, particularly by clubs and influential figures within Serbia who would like its ABA members to better enhance domestic competition, such as Serbian national-team coach Svetislav Pesic.

The competition was agreed upon in principle at a meeting in Ljubljana on 3 July 2001 by a founding assembly containing representatives of four basketball clubs: KK Bosna, KK Budućnost, KK Cibona, and KK Olimpija. The day is considered to be the league's foundation date. Though club representatives from four countries attended the meeting, the main individuals behind the venture were six Slovenians and Croatians: Roman Lisac, Zmago Sagadin (at the time head coach of Olimpija), Radovan Lorbek (at the time president of Olimpija), Josip Bilić, Danko Radić, and Bože Miličević (at the time president of Cibona). The name chosen for the competition was the Adriatic League, invoking the Adriatic Sea as a common thread for participant countries thus purposely avoiding the terms 'Balkans' or 'Yugoslavia' that at the time carried a fairly undesirable public perception in Slovenia and an extremely negative one in Croatia. Sidro d.o.o., the commercial entity that runs it, was created two months later in Slovenia.

On 28 September 2001, the league announced a five-year sponsorship deal with Slovenian company Sava Tires from Kranj, a subsidiary of Goodyear Tire and Rubber Company. The deal also included naming rights, hence from 2001 until 2006, the competition was known as the Goodyear League.

With twelve clubs taking part in the inaugural 2001–02 season, the competition commenced in fall 2001 with four teams from Slovenia, four teams from Croatia, three teams from Bosnia-Herzegovina, and one team from FR Yugoslavia. The first game was contested in Ljubljana between Olimpija and Široki on Saturday, 29 September 2001 at 5:30pm.

Though the competition purported to gather the strongest sides from former Yugoslavia, as mentioned, teams from Serbia were noticeably absent, particularly Belgrade powerhouses and biggest regional crowd draws Partizan and Crvena zvezda. In addition to no clubs from Serbia proper, the league had no Serb-dominated clubs from Bosnia-Herzegovina either. Since the league founders mostly avoided talking about the issue due to fears of media backlash, the fact that no invitations were extended to Serbian clubs was generally explained through security issues due to organizers' fears of crowd trouble if Croatian and Serbian clubs were to start playing again in the same competition. Then in early February 2002, the public got a preview of just that when Cibona and Partizan met in Zagreb as part of that season's EuroLeague group stage. In a nationalistically charged and incident-filled encounter, Croatian fans peppered the Partizan players with rocks, flares, and even ceramic tiles before physically assaulting Partizan head coach Duško Vujošević in the guest team dressing room after the game.

The Adriatic League debut season was marked by dwindling attendances and lukewarm media support. Still the league did receive a bit of a shot in the arm on 24 February 2002, when its managing body ABA got accepted as full member of ULEB.

For the 2002–03 season, the league remained at the total number of 12 teams, while it went through major re-tooling internally. By the time season started, four teams dropped out (Sloboda Dita, Budućnost, Triglav, and Geoplin Slovan) to be replaced by: Israeli powerhouse Maccabi Tel Aviv, Crvena zvezda (the first team from Serbia in the competition), the Bosnian outfit KK Borac, and Croatian club KK Zagreb.

It was important for the league's long-term business to negotiate acceptable terms for the Serbian clubs to join the competition. To that end, Lorbek and Lisac went to Belgrade in early April 2002 with an offer of taking in three clubs from FR Yugoslavia for the Adriatic League's 2002–03 season. The offer was flatly rejected initially by the representatives of five YUBA Liga clubs – Partizan, Crvena zvezda, Hemofarm, FMP, and Budućnost – as their unified platform was either all five or nothing. Taking in all five required expanding the league to 14 teams, which was something the league organizers weren't prepared to do due to the associated increase in operating costs. The negotiated agreement thus fell through for the time being. However, it didn't take long for dents to appear in the unified front put forth by five YUBA league clubs – in May 2002 Crvena zvezda's management (three businessmen close to the ruling Democratic Party in Serbia: Živorad Anđelković, Igor Žeželj, and Goran Vesić) hired Zmago Sagadin to be the club's new general manager – and soon after, in June 2002, the club broke the ranks by negotiating terms on its own thus agreeing to join the Adriatic League for the 2002–03 season.

For the 2003-04 season, the league expanded to 14 teams, while relegating KK Bosna; meanwhile, Maccabi Tel Aviv departed the league in the wake of political unrest in Serbia. In replacement, 4 teams joined: KK Reflex of Serbia (who would win the league in their first season), Lovćen 1947 and Budućnost of Montenegro, and KD Slovan of Slovenia. The latter two of those returned to the league after a year's absence, having been relegated from the 2001–02 season. In the 2004-05 season, the league expanded again to 16 teams while relegating 3, and its Final Four tournament became a Final Eight. Its clubs included for the first time Serbian powerhouse Partizan, and another Serbian former-holdout club, Hemofarm (who would win the league in its first year participating). After the season, the league contracted down from 16 back to 14 clubs, a number it would stay at until the 2017-18 season. In September 2006 the league signed a general sponsorship contract with Nova ljubljanska banka (NLB) and was renamed to NLB League, while keeping Goodyear as one of the major sponsors. The league's first all-star game was held in December 2006 in Ljubljana.

For the 2011-12 season, Israeli club Maccabi Tel Aviv rejoined the Adriatic League for one season, winning it. In 2012, a team from North Macedonia participated for the first time, with MZT Skopje Aerodrom joining the league for the 2012-13 season.

A conflict emerged in early 2015 between the ABA and FIBA Europe, resulting in the former's loss of recognition by the latter, as a part of the broader FIBA–EuroLeague dispute. On 13 April 2015, ABA League signed a 4-year agreement with Euroleague Basketball for one EuroLeague and 3 EuroCup annual slots. Because of this agreement, FIBA threatened to suspend the six constituent national federations, and on 30 April it suspended ABA League from membership. FIBA wanted the league controlled by the national federations and clubs, while the ABA's organizing corporation, Sidro, wanted to maintain independence. A restructuring proposal from the league's clubs to FIBA in June 2015 involving reincorporating the competition under a new legal entity owned by the clubs was approved by FIBA, and the league's recognition reinstated. The next April, however, FIBA nevertheless suspended 8 nations' ability to have their senior men's national teams participate in EuroBasket 2017, including all 6 constituent members of ABA League plus Russia and Spain, and further threatened their ability to participate in the 2016 Olympics. The suspension of the ABA League was continued by FIBA in May 2016, and letters sent by FIBA to the national associations insisted that any federation that was associated with Euroleague would be punished similarly. Analysis later that year suggested that FIBA's goal was to apply leverage to Euroleague in their dispute by depriving Euroleague's competitions of their ABA League club participants. With the emergence of a FIBA-Euroleague truce in mid-2016, FIBA Europe announced in May 2016 that no federations or teams would, in the end, be suspended from national competition. Despite this, and despite their clubs' continued participation in EuroLeague and EuroCup, the ABA League has not re-joined ULEB as of 2023.

Following the 2016-17 season, and in keeping with their restructuring agreement with FIBA, the league elected to split into two divisions: the relegated team(s) from the First Division would join the Second Division the following year, and the latter promoting to the former, with 12 teams initially in each division (reduced from 14 previously). The Second Division would be composed of the top-finishing clubs of each country's domestic league in the previous season who were not already participating in the ABA League. The allocation of teams between countries was a contentious process, but the reorganization yielded a 25% jump in attendance for the First Division's next season.

In October 2023, the ABA League's sports director told news media of the league's intention to have a team from Dubai join the competition, and possibly for the city to host an ABA League Final Four competition. On 19 March 2024, the league officially announced BC Dubai would join the league starting from the 2024–25 season, obtaining a license for three seasons.