Where was Lord Muruga born?
According to the Śiva Purāṇa and the Skanda Purāṇa, Lord Muruga—Kārttikeya or Skanda—manifested in Śaravaṇa, a grove of reeds situated on the sacred bank of the celestial river Gaṅgā. The narrative is placed in the Himalayan region, although the Purāṇas do not identify a present-day town.
Skanda Purāṇa reference
Skanda Purāṇa, Māheśvara-khaṇḍa, Kedāra-khaṇḍa, Chapter 27, verse 79
गङ्गायाः पुलिने जातः कार्त्तिकेयो महाबलः ॥
gaṅgāyāḥ puline jātaḥ kārttikeyo mahābalaḥ
Meaning:
“The mighty Kārttikeya was born on the sandy bank of the Gaṅgā.”
The surrounding passage, Chapter 27, verses 75–80, places the event in the Himalayan–Gaṅgā setting: the divine energy descended from the Himalaya into Gaṅgā, was surrounded by reeds or bamboo growth, and manifested as the six-faced child on Gaṅgā’s bank.
Conclusion
The Purāṇic answer is:
Lord Muruga was born or manifested at Śaravaṇa—the sacred reed grove on the bank of the celestial Gaṅgā, in the Himalayan region.
This is why he is called:
Śaravaṇabhava — “the one born in Śaravaṇa”
Gāṅgeya — “the son associated with Gaṅgā”
Kārttikeya — “the child nurtured by the Kṛttikās”
Ṣaṇmukha — “the six-faced Lord”