Complex sentence: After the Battle of Mohács in 1526 the central and eastern parts of the plain were included into Ottoman Empire, and the remains of the Kingdom of Hungary in the north-west joined the Habsburg Monarchy, where they were called Royal Hungary.
Split into simpler sentences: After the Battle of Mohács in 1526 the central part of the plain was conquered by the Ottoman Empire. The remains of the Kingdom of Hungary joined the Habsburg Monarchy, where they were called Royal Hungary.