Murugan is the southern form of Kartikeya, son of Shiva. Or rather, Kartikeya, son of Shiva, is the northern form of Murugan. In Tamil Sangam literature, dating to 1,500 years ago, and referring to earlier oral tradition, Murugan is associated with mountains. This was the period that Vedic ideas became increasingly prominent in the southern half of India. Thus, the barren desert came to be associated with goddess Kali, the sea shore with Varuna, the forests with Vishnu and the fields with Indra. Murugan stood atop mountains, and came to be associated with Shiva, as his son, indicating Shiva as an over-arching divinity, although in local legends, Shiva himself learns the secret of Pranava (the ‘om’ sound) from Murugan, which makes Murugan the teacher of his father. Most north Indians are unfamiliar with this story, but it quite popular in Tamil Nadu that boasts Arupati Vitu, the six temples of Murugan that make a popular pilgrim route. Though the shrines may be older, the temples we see now were built in various phases in the past 1,000 years by various kings.
The six temples also indicate the different events in the life of Murugan. At Swamimalai, he is the son who revealed the secret of ‘om’ to his own father, and even to Brahma, the creator, who pretended to know the Vedas, when all he knew were the words, not the meaning. At Palni, one of the most popular shrines, he is the young student bearing a staff, Dandapani, who left his father’s abode, at Mount Kailasa, as his father favoured Ganesha over him.