During what period did the Persian state reach its greatest power?

The period of the greatest power of the Persian state falls, in my opinion, during the reign of King Darius I. This king waged numerous and successful wars, be it external campaigns or the suppression of rebellions. Darius was able to expand the borders of the state. Along with this, Darius carried out numerous reforms. It is worth mentioning here the monetary reform, the agrarian reform, the division of the vast state into satrapies. Trade developed, for this purpose the construction of roads and canals was launched. New cities were also built.