Hi John,
I know your message was a few years ago but I have some information related to the Donohoe's from Derrycassan and around that area.
My 4x great grandfather was Hugh Donohoe, I believe from Derrycassan. I don't have a date of birth for him but would estimate around 1800 based on my 3X great grandmother, Catherine Donohoe, being born in 1831.
Most of the records I have seen show links to the areas of Drumane, Clintycarnahan, Lecharrownahone and Derrycassan. Confirmed records show the names of Donohoe, McGovern, Reilly, McGerty (various spellings), and McGuire.
Catherine Donohoe, My 3x great grandmothers death records show her parents were Hugh Donohoe and Cecelia McGovern. Catherine married 1st to a Bernard Gunn and then second to a Patrick McGuire in Clintycarnahan. My 2x great grandmother was Margaret Gunn from Catherine's first marriage.
This family all moved to Glasgow, Scotland between 1865 and 1868. Marrgaret Gunn married Bernard McGarrity (McGerty) in Glasgow but he was also from Drumane / Clintycarnahan. Bernard McGerty's parents were Patrick McGerty (Drumane) and Bridget Reilly. You will notice the theme in the names from Gerards post above.
Other names linked were McGinn (Derrycassan), Prior (Derrycassan), Dolan, Baxter, Brady, Smith/Smyth, Freehill among others.
The families appear to have left Cavan in large numbers between 1865-1870 but i've never been able to find out the exact reason why. There were Donohoes, McGerty's, Reilly's, McGuire's and McGinns all living together in same block of flats in Lancefield Street, Glasgow, in the 1871 census and many remained there for decades.
I've found the Bawnboy page below quite helpful to see the different family names in each area.
Bawnboy & Templeport Genealogical & Historical Data
Thanks
Allan McGarrity