Valmiki Ramayana Kishkindha Kanda Sarga 50 Shloka 4
Original Shlokaस हि देशो दुरन्वेषो गुहागहनवान्महान्। तत्र वायुसुतस्सर्वं विचिनोति स्म पर्वतम्।।4.50.4।।
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गुहागहनवान् a difficult mountain range, caves and woods, महान् great, सः देशः that place, दुरन्वेषः difficult to search in, वायुसुतः son of the Windgod, तत्र there, सर्वम् all, पर्वतम् mountains, विचिनोति स्म had searched.
The son of the Windgod, Hanuman, searched all over the mountains and caves and woods difficult to access in that southwestern region of the mountain.