Why did it become difficult for the Sassanid Empire to relive the glory of the first Persian Empire

Alexander the Great had conquered the Persian Empire, and on hisdeath it was dividedup by his generals into the HellenisticKingdoms – principally Macedonia, Egypt and Syria, plus transitoryones in Asia Minor.

This took away the entire western half of the old Persian Empire.And as the power of the Hellenistic Kingdoms waned, it was replacedby the expansion of a rising Rome. In addition, the Indiansub-continent was taken over by rising powers there. So the richestparts of the Persian Empire were permanently denied to Sassanidexpansion.