Mining was most important in the economy of the state, though it developed only in the 13th century and fully blossomed in the 15th century, amidst the most turbulent period in the state's history. The mining intensified the trading turnover, enhanced the building and expansion of the cities and empowered the citizens' class in them. At the beginning of the 15th century, Serbian respot Stefan Lazarevć (d. 1427) issued the Mining Code. The new relations and social forces, already turning traditional in the Serbian feudal society were nipped in the bud by the Ottoman destruction of the Serbian state. For the entire economy, and especially the mining, the period of primitiveness and regression began.