Emperor Taizu developed an effective centralized bureaucracy staffed with civilian scholar-officials and regional military governors and their supporters were replaced by centrally appointed officials. This system of civilian rule led to a greater concentration of power in the central government headed by the emperor than had been possible during the previous dynasties. In the early 11th century, there were some 30,000 men who took the prefectural exams per year (see imperial examination), which steadily increased to roughly 80,000 by the end of the century, and to 400,000 exam takers during the 13th century. Although new municipal governments were often established, the same number of prefectures and provinces were in existence as before the Song came to power. Thus although more people were taking exams, roughly the same number were being accepted into the government as in previous periods, making the civil service exams very competitive amongst aspiring students and scholars.