Before the reforms of the 19th and 20th centuries, the state organisation of the Ottoman Empire was a simple system that had two main dimensions, which were the military administration and the civil administration. The Sultan was the highest position in the system. The civil system was based on local administrative units based on the region's characteristics. The Ottomans practiced a system in which the state (as in the Byzantine Empire) had control over the clergy. Certain pre-Islamic Turkish traditions that had survived the adoption of administrative and legal practices from Islamic Iran remained important in Ottoman administrative circles. According to Ottoman understanding, the state's primary responsibility was to defend and extend the land of the Muslims and to ensure security and harmony within its borders within the overarching context of orthodox Islamic practice and dynastic sovereignty.