O child, that Yuga was called Krita when only one true eternal religion was extant. In that best of Yugas everyone had religious perfection. There was no need for performing (any) religious act.
हनूमानुवाच कृतं नाम युगं तात यत्रधर्मः सनातनः। कृतमेव न कर्तव्यं तस्मिन् काले युगोत्तमे॥