What is a concept that results in material being produced only when requested and moved to where it is needed just as it is needed?

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.

rain should be the answer.

good question. i'll be looking into that. (this is a joke sir)