Azerbaijan is one of humanity's most ancient sites. There were inhabited settlements in Azerbaijan even at the earliest stages of human development, and people have been present throughout history. States mainly inhabited by people of Turkic origin have existed in the territory of historical Azerbaijan since the third millennium B.C. The Roman Empire briefly established a colony in the region, naming it Albania (unrelated to the present-day Albania.) Beginning in the seventh century, Arabs dominated the area, introducing Arabic and Islam, which replaced Zoroastrianism and Christianity as the major religion. While Arabic did not replace the existing languages, its script was used for the Azerbaijani language until 1924. Because of its geographical location at the juncture of Europe and Asia, the area was ruled by Turkey or Iran (Persia) for much of its history, as well as by Mongols and Russians. In the 1813 and 1828 treaties between Russia and Iran, northern Azerbaijan became part of Russia, while the south became part of Iran. Ever since, the divided Azerbaijanis have experienced different destinies. Present-day Iran has an Azerbaijani population of 20 million to 30 million-one-third of Iran's population. Although it was difficult for relatives to visit one another across the border during the Soviet era, people are now able to maintain much closer ties. Azerbaijan declared its independence in 1918 and was the first established democratic Republic in the East, but was suppressed by Russia's Red Army in 1920. In 1922, Azerbaijan became a Soviet Socialist Republic, remaining so through 1991. A conflict with Armenia erupted in the late 1980s in the area of Nagorno-Karabakh, which is part of Azerbaijan, but is inhabited mostly by ethnic Armenians. It became the subject of fierce fighting as the Armenians sought self-determination rights. Between 1988 and 1994, Armenians in the region assumed control over areas between Nagorno-Karabakh and the Armenian border. It declared itself the Independent Republic of Mountainous Karabakh, but no other nation in the world, aside from Armenia, recognizes its legitimacy. A United Nations-brokered cease fire occurred in 1994, the effects of which ended diplomatic relations between Armenia and Azerbaijan. The war had displaced roughly 900,000 people and left Armenian troops with 20 percent of Azerbaijan's land. As Soviet central authority weakened in 1990, the Azerbaijan Popular Front emerged in opposition to the local communist party. Yet it was Azerbaijani communist leaders who declared independence in 1991, a few months before the Soviet Union dissolved. Abulfaz Elchibey of the Popular Front won the country's first presidential election in 1992, but a year later, in the wake of political, economic, and military upheaval, surrendered the office to Heydar Aliyev. Aliyev, a former communist leader, was named interim president. Aliyev soon held elections and won 97 percent of the vote. His son, Ilham Aliyev, was elected president in October 2003 after his father declined to run for office due to his poor health. Heydar Aliyev passed away two months later. In October 2008, Ilham Aliyev was elected for another five-year term. Up until 2009, each president was limited to two five-year terms, but in March 2009 a referendum was passed, eliminating the two-term limit.