इह here, आगतम् came, तं सुग्रीवम् that Sugriva, असहायम् without any help, न मन्ये not think so, अवष्टब्धसहाय certainly sought refuge, यम् big, आश्रित्य having taken help, एषः he, गर्जति is roaring.

'Certainly Sugriva has not come here to give a warcry without any external help. The person whose refuge he has sought is not a small one.