Canto 3 -
Araṇya-kāṇḍa
Chapter 12: Agastya Requests Rāma to Protect the Sages
Text 3.12.57

वृक्षगुल्मलताहीनं तापसैरभिवर्जितम्।
कान्तारमभवत्तात घोरं परमदारुणम्।
योजनार्धसहस्रं तु विन्ध्यपादस्तु दक्षिणः॥

vṛkṣa-gulma-latā-hīnaṁ tāpasair abhivarjitam
kāntāram abhavat tāta ghoraṁ parama-dāruṇam
yojanārdha-sahasraṁ tu vindhya-pādas tu dakṣiṇaḥ

vṛkṣa-gulma-latā-hīnam = without trees, shrubs and creepers; tāpasaiḥ = of ascetics; abhivarjitam = and devoid; kāntāram = forest; abhavat = it became; tāta = dear child; ghoram = a terrible; parama-dāruṇam = and extremely fierce; yojana-ardha-sahasram tu = that spread five hundred yojanas; vindhya-pādaḥ tu = at the foot of Vindhya; dakṣiṇaḥ = in the south.

Dear child, without trees, shrubs and creepers, and devoid of ascetics, it became a terrible and extremely fierce forest that spread five hundred yojanas at the foot of Vindhya in the south.