In abbasid period750-1258what is the meaning of this statement With in 150 years of gaining power they were force to cede their power to local dynastic ameers?
The statement is pretty self-explanatory. It means that
initially the Abbasids took the power but within 150 years, their
power had declined. As a result, local rulers who were previously
controlled by the Abbasid king became free and so the rule of
abbasid was broken and the power was split among the small local
and tribal leaders.