Complex sentence: The government was originally able to control most of its internal affairs due to the firm support provided by the people, but as time went on the rulers' abuse of the other social classes led to social unrest and instability.
Split into simpler sentences: The government was originally able to control most of its internal affairs due to the firm support provided by the people. As time went on, however, the rulers' abuse of the other social classes led to social unrest and instability.