Al-Kulayni was born in Kulayn, a village or small town situated near Rey, Iran.[4] His father was Ya’qub al-Kulayni, who is buried at Rey. He lived in the era of the Minor Occultation of Hujjat-Allah al-Mahdi, the last of the Twelve Imams who, according to Shia belief, is currently in occultation and will certainly appear before the Day of Judgment). He is claimed to have greatly benefited from al-Mahdi’s divine knowledge by interacting with him through the Imam’s Deputies.