A satrap was a provincial governor during ancient Persian imperial times.
Satraps ruled the various provinces of Persia from the age of the Median Empire, 728 to 559 BCE, through the Buyid Dynasty, 934 to 1062 CE. At different times, Persia's empire stretched from the borders of India in the east to Yemen in the south, and west to Libya.
When Alexander the Great died in 323 BCE, his generals divided up his empire into satrapies, so that each of them would have a territory to rule under the Persian title. These Diadochi, or "successors," ruled their satrapies until each one fell between 168 and 30 BCE.
The term "satrap" is derived from the Old Persian kshathrapavan, meaning "guardian of the realm." In modern usage, it can mean a despotic lesser ruler, or a corrupt puppet.
"When the satrap of Yemen converted to Islam in 630, his subjects enthusiastically followed his lead."