Valmiki Ramayana Ayodhya Kanda Sarga 102 Shloka 40

बहुभि: by several, यानैः by vehicles, खुरनेमि समाहता crushed with hooves and wheels, सा भूमिः the earth, अभ्रसमागमे at the gathering of stormclouds, द्यौरिव like the sky, तुमुलम् tumultous, शब्दम् sound, मुमोच emitted.

The earth crushed by several vehicles, hooves (of horses) and wheels (of chariots) emitted tumultuous sounds like the sky in the gathering stormclouds.