What is meant by main drain

the principal lengthwise pipe of a ship's bilge drainage system

The principle lengthwise pipe of a ship's bilge drainage system

ideology

explanation:

in 342 bc j._c. egypt fell into the hands of the persians, under the reign of nectanebo ii

greek city-states unite in a revolt against the persian empire at the beginning of the fifth century bc. j.-c  

from the year 660 or 659 bc ad, cyrus preached the revolt against the medes to deliver the persians.