How did the royal road benefit the persians? it prevented invaders from entering the persian empire. it encouraged the building of persian naval vessels. it established communication throughout the persian empire. it the persians reach rome and then conquer it.

The Royal Road was an ancient highway rebuilt by Darius the Great in the 5th century BC, it permitted mounted couriers to travel 1677 miles, from Susas to Sardis, in nine days and so it established communication throughout the Persian Empire. Herodotus, an ancient greek historian, wrote that "There is nothing faster in this world than these Persian couriers".

The Royal Road was an ancient highway rebuilt by Darius the Great in the 5th century BC, it permitted mounted couriers to travel 1677 miles, from Susas to Sardis, in nine days and so it established communication throughout the Persian Empire. Herodotus, an ancient greek historian, wrote that "There is nothing faster in this world than these Persian couriers".

after defeating german forces in north africa allied leaders turned their attention to "italy," since this was the location that made the most geographic sense before invading northern europe via france. 

the lines on a surface map are called isobars. isobars are lines of constant pressure which are measured in units called millibars. the numbers indicate the amount of air pressure, in millibars, that each line represents.