Guru Nanak, the founder of Sikhism, was active during the time of the Lodi dynasty's decline in the late 15th and early 16th centuries, coinciding with Babur's conquest of India in 1526. His teachings emphasized a direct connection with God, communal harmony, and rejection of caste divisions, which were pivotal during a period marked by political upheaval and social transformation. In contrast, Dadu Dayal and Tyagaraja emerged later, with Dadu Dayal's activity primarily in the 16th century and Tyagaraja in the 18th century, thus making Guru Nanak the only saint among the three whose preaching coincided with this significant historical transition.