Valmiki Ramayana Kishkindha Kanda Sarga 48 Shloka 6
Original Shlokaस तु देशो दुरन्वेषो गुहागहनवान्महान्। निर्जलं निर्जनं शून्यं गहनं रोमहर्षणम्।।4.48.6।।
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गुहागहनवान् a location with impenetrable caves, महान् great, सः देशः that place, दुरन्वेषः is difficult to search, निर्जलम् with no water, निर्जनम् no people, शून्यम् desolate, गहनम् impassable, रोमहर्षणम् terrific.
They searched in dense forests, interior locations impassable, desolate and terrific, without water, and people.