The celestials with Sakra (Indra) at their head did not like to be seen and therefore they made this place inaccessible by raising up hills.
ते दर्शनं त्वनिच्छन्तो देवाः शक्रपुरोगमाः। दुर्ग चक्रुरिमं देशं गिरि प्रत्यूहरूपकम्॥