The conquest of the Balkans by the Ottomans set in motion important population movements, which modified the ethnic and religious composition of the conquered territories. This demographic restructuring was accomplished through colonization of strategic areas of the Balkans with Turks brought or exiled from Anatolia, establishing a firm Turkish Muslim base for further conquests in Europe. Ottoman Empire used colonization as a very effective method to consolidate their position and power in the Balkans. The colonizers that were brought to the Balkans consisted of diverse elements, including groups uneasy for the state, soldiers, nomads, farmers, artisans and merchants, dervishes, preachers and other religious functionaries, and administrative personnel. Among the earliest arrivals were large numbers of pastoral peoples such as the Yürüks, Turcomans (Oghuz Turks), Tatars from Anatolia and Crimean Tatars (Qaraei or Kara Tatars) led by their chieftain Aktav. As the Ottomans expanded their conquests in the Balkans, they brought nomads from Anatolia and settled them along the main highways and in the surrounding mountain regions. Densely populated Turkish colonies were established in the frontier regions of Thrace, the Maritsa and the Tundzha valleys. The colonization policies already begun under Orhan were continued by his successors Murat I (1360–84) and Bayezit I (1389–1402). Additional colonists, mostly nomads again, were established along key transportation and communication routes in Thrace, Macedonia, and Thessaly. The Ottoman authorities maintained these nomads in their tribal organization through the 16th century and began to settle them only during the 17th century.