Pereyaslav-Khmelnytskyy (pĕrˈĕyəsläfˈ-khmĭlnyĭtˈskē) [key], town, in Ukraine, on the Trubezh River. It was known in 907 and served as the fortified capital of the duchy of Pereyaslavl (11th–13th cent.). By 1239 the city was in ruins after Tatar attacks. In the second half of the 16th cent. it began to grow as a center of the Ukrainian Cossacks. In 1654, Bohdan Chmielnicki and his Cossacks met at Pereyaslavl to agree that Ukraine, for protection against Poland, become a protectorate of Russia. This alliance, however, led to the complete domination of Ukraine by Russia. It is on this agreement that all later Ukrainian claims to autonomy were based (see Ukraine). The city was called Pereyaslavl until 1943, when it was renamed in honor of Chmielnicki. Besides a historical museum, it has remains of the Cathedral of St. Michael (founded 1089), the monastery of St. Michael (17th–18th cent.), and the Cathedral of the Ascension (1695–1700).