Valmiki Ramayana Yuddha Kanda Sarga 41 Shloka 99

राक्षसाः Rakshasa, दीनाः desperate, कपिभिः even monkeys, व्याप्तम् spread over, कृत्स्नम् dark, प्राकारपरिखान्तरम् entire area from the boundary and moat, नानरीकृतम् filled with monkeys, प्राकारम् boundary, ददृशुः saw, राक्षसाः Rakshasas, भयम् fear, आगताः reached, हाहाकारम् making noise, प्रकुर्वन्ति converted to defensive walls.

The Rakshasas were desperate to see the spread of monkeys over the entire area from the boundary to moat of Lanka. The way the space between was filled with Vanaras seemed as though the Vanaras converted into boundaries. Rakshasas were seen making a loud noise.