Darius 1 was the son in law of Cambyses ,The son of Cyrus the great. He added the regions of Punjab in India and Thrace in Europe . He had a history of battles , victories, and succession inscribed in three languages in cuneiform script on a rock face in Behistun, near the city of Kermanshah in western Iran. The Behistun Inscription starts with a brief autobiography and lineage and the ancestry of Darius 1 and also includes the names of the 23 satrapies(provinces) . Darius 1 set up an efficient government by dividing the empire into provinces or satrapies , each ruled by a governor called Satrap . To keep a check on the satrap a military officer was stationed in each province to represent the "Great King, King of Kings "Shahenshah" (Urdu language word) . Special inspectors were appointed as the eyes and ears of the king , they travelled through out the empire and reported to the king .

 Darius 1 set up proper rules for his government and introduced a monetary system ; a new postal system  was also set up which had relay stations known as Chapar khaneh (in Urdu language) through out the empire. The policies of Cyrus and the administration and progress under Darius 1 strengthened the empire. Darius 1 died in 486 BCE .