Founded in the seventh century by Ajaipal Chauhan, Ajmer derives its name from Ajay Meru. Ajay Meru is the invincible hill, at the foot of which the city stands today. Surrounded by the Aravalli mountain range, Ajmer is an oasis. Ajmer is a popular pilgrimage; the Dargah Sharif, where the tomb of the Sufi Saint Khwaja Moinuddin Chisti is revered by the Muslims. Ajmer is also the base for tourists who are visiting Pushkar, the abode of Lord Brahma; Pushkar Lake is a sacred spot for the Hindus. During Kartika which falls in the months of October and November, devotees throng to Pushkar in large numbers to take a dip in the sacred lake.