The newest nation, Kosovo, is ethnically speaking Albanian. Though Albania itself is a sovereign nation of its own, which borders Kosovo.
Albanians are largely Muslim. How did that happen? you ask:
The Albanians are a genuine nation. Their national symbol derives from a seal of their national hero George Kastrioti, alias “Skanderbeg.” He led an independent Albania from 1443 until his death in 1468. After having served in the Turkish Ottoman army, Skanderbeg rebelled in 1443. He choose a Roman/Byzantine eagle as his standard, abjured his Muslim faith and liberated the Roman-Catholic Albanians, thereby halting the advance of Islam into Christian Europe. Ten years after his death, in 1478, Albania was conquered by the Turks who ruled it until 1912 and imposed Islam. Over 400 years of Ottoman rule resulted in a nation that has a 70% Muslim majority, though it proudly displays the Roman eagle and has Skanderbeg, a Muslim apostate and a defender of Christianity, as its national hero. Such are the ironies of history.
The province of Kosovo lies to the northeast of Albania. It, too, was originally inhabited by Illyrians but by 850 it had become the heartland of the Slavic Serbs. In the 14th century it fell to the Ottomans. The Turkish occupation imposed Islam and brought in Muslim Albanians. When the province was reunited with Serbia in 1912, the Muslim Albanians had already begun to replace the Christian (Orthodox) Serbs as the predominant people in the province. Today, owing to their demographic growth, 90% of Kosovo is Muslim and Albanian.
From HERE.