Valmiki Ramayana Aranya Kanda Sarga 11 Shloka 82

यस्य by whose, प्रभावात् by his power, राक्षसैः by the demons, इयम् this, दक्षिणा दिक् southern side, त्रासात् out of fear, दृश्यते is seen, नोपभुज्यते cannot be enjoyed, तस्य that Agastya's, आश्रमपदम् hermitage, इदम् this is.

This is his hermitage. On account of his (Agastya's) impact the demons look south but cannot eat the hermits out of fear (for the sage).