How did the Royal Road effect cultural diffusion in the Persian Empire

Its primary function was to facilitate land communication acrossthe empire later copied by the American pony express.

Sections of this road were used for normal travel by foot, horse,donkey and wagon, however this was slow and expensive for anythingbeyond local travel – more than 50 miles. Sea and river transportwas the preferred means for moving cargo and people where it wasavailable.