The issue has soured the relations of Bulgaria with former Yugoslavia and later with the Republic of North Macedonia for decades. Kiro Gligorov, the president of Yugoslav Macedonia, sought to keep his republic outside the fray of the Yugoslav wars in the early 1990s. Yugoslav Macedonia's very existence had depended on the active support of the Yugoslav state and Communist Party. As both began to collapse, the Macedonian authorities allowed and encouraged a stronger assertion of Macedonian national identity than before. This included toleration of demands from Macedonian nationalists for the reunification of Macedonia. The Albanians in the Republic of Macedonia were unhappy about an erosion of their national rights in the face of a more assertive Macedonian nationalism. Some nationalist Serbs called for the republic's re-incorporation into Serbia, although in practice this was never a likely prospect, given Serbia's preoccupation with the wars in Bosnia and Croatia and the relatively small number of Serbs in the Republic of Macedonia compared to Croatia and Bosnia and Herzegovina. As communism fell throughout Eastern Europe in the late 20th century, Yugoslav Macedonia followed its other federation partners and declared its independence from Yugoslavia in late 1991. In 1991, the (then Socialist) Republic of Macedonia held a referendum on independence which produced an overwhelming majority in favour of independence. The referendum was boycotted by the ethnic Albanians, although they did create ethnic political parties and actively contributed in the Macedonian government, parliament etc. The republic seceded peacefully from the Yugoslav federation, declaring its independence as the Socialist Republic of Macedonia. Bulgaria was consequently the first country to officially recognize the Republic of Macedonia's independence – as early as February 1992, followed by other countries as well. The new Macedonian constitution took effect 20 November 1991 and called for a system of government based on a parliamentary democracy. Kiro Gligorov became the first President of the new independent state, succeeded by Boris Trajkovski. In early January 2001 armed conflict took place between the ethnic Albanian National Liberation Army (UÇK) militant group and the Republic of Macedonia's security forces. The conflict partially ended with the signing of the Ohrid Framework Agreement by the government of the Republic of Macedonia and Albanian representatives on 13 August 2001, which provided for greater rights for Macedonian Albanian population. In January 2002, the Macedonian conflict ended when the amnesty was announced to Albanian irregulars and rebels. Occasional unrest continued throughout 2002. Slavs first arrived in the region late 6th and early 7th centuries AD when Slavic-speaking populations overturned Macedonia's ethnic composition.