Authority or leadership in Islam (Shiea)

According to Shiea, God has sent the prophets in order to guide humanity. And the earth has never been free from the friends of God. Because the Prophet of Islam was the last of the prophets. And 1400 years have passed since his Prophet. So it is not logical that God sent 124,000 prophets to the people before Islam. But no one has been appointed for the post-Islam era. Therefore, the Shiites believe that God has given the Imams a continuation of human guidance after the Prophet.