Final answer:
Guru Nanak Dev Ji achieved Joti Jot in 1539 at Kartarpur Sahib, marking a significant event in Sikh history and the end of his earthly journey.
Step-by-step explanation:
Guru Nanak Dev Ji became 'Joti Jot' (immersed in the Eternal Light) in the year 1539 at Kartarpur Sahib. He was the founder of Sikhism and the first of the eleven Sikh Gurus. His teachings and life had a profound impact on the Punjab region, leading to the establishment of a religion that emphasized equality among all humans and rejected the caste system. Guru Nanak Dev Ji's Joti Jot is a significant event in Sikh history, marking the end of his earthly journey and the beginning of his eternal union with the divine.