Here is some info about a Daniel Ruark of MD who fits your timeframe. I have not researched this line and have no way of knowing whether this is the correct person. You will need to do additional research. If you haven't already, you should check out the MD deeds, which are online, to see if you find your Daniel selling land around the time you think he left MD. These early Ruarks were clustered in the Worcester Co, MD area.
Daniel Ruark b. c1763 Worcester Co, MD; d. 1838 Worcester Co, MD; son of Ezekiel Ruark and Rachel Esham. This Daniel Ruark left heirs James Ruark, William Ruark, DANIEL RUARK, Joel Ruark, Wheatley Ruark, and Mary Ann Ruark. If Daniel Sr. was born in 1763, he could be the father of your Daniel b. c1789. Good luck.