Early 1700's Henry O'Hara, John OHarrow

My 4G Henry O'Hara (b 1730 in Ireland) and supposed 5G John O'Harrow (b 1705 in Trabsazon Turkey???) grandfathers are a mystery. If John is my 5G grandfather, how might he have come to be born in Turkey? What might his father have been doing there and what was his name and origin?
Henry came to America between his birth and marriage in 1759 and lived and died in Maryland. What might have caused him to leave his homeland and come to America. Poverty, or opportunity, or escape?
His son Henry moved to Illinois and established our family farm by 1819.
Any help with this would be greatly appreciated.
I would love to know if I have relatives on the old sod.
Mark O'Hara