When Anastasius became emperor the once vast number of Roman mints had been reduced to only two: Constantinople and Thessalonica. Thessalonica did not strike Byzantine copper coinage until the reign of Justin I. The mint closed about 630 but opened again under Alexius I (1081 - 1118) and operated until the 14th century for various despotates, kingdoms and empires that took the city as their capital. In 1423, Despot Andronicus, ceded Thessalonica to the Republic of Venice to protect it from the Ottomans who were besieging the city. The Venetians held Thessaloniki until it was captured by the Ottoman Sultan Murad II on 29 March 1430.