Can you be any more specific with your question? Are you referring to a [Bindi] (http://en.wikipedia.org/wiki/Bindi_%28decoration%29#mediaviewer/File:Kullu_Himachal_Pradesh_India_Woman.jpg)?

There is no such thing as an Eastern Monk for starters. As far as I know, monks only exist within Buddhism and Jainism (in terms of Asian religions). I can't find any evidence for Buddhist monks using bindis, as it is generally assosciated with women and Hinduism. In Hindusim, Bindis have been used to mean a number of different things, ranging from 'enhancing one's beauty' to being the 'agna' which is the place of concealed wisdom within oneself.

There was also a phase in the Tang Dynasty of China (618-907CE) in which people wore marks on their forheads for decorative purposes. But again, I can't find any evidence that says Monks wore them.