Hi there,
Do you have any idea what part of County Monaghan they were from? Knowing the exact place of origin makes a big difference when carrying out research. For instance, I would be able to recommend relevant church records or estate records if I knew an exact place of origin.
I can still suggest some records for you to look at. In the meantime, dust down any family documents, letters or bibles and see if there are any clues written down to help narrow down the place of origin in County Monaghan.
You could try checking the land records called the Tithe Applotment Books (1823-38) or the later Griffth's Valuation (1848-64). Griffith's is freely available here: www.askaboutireland.com or here: www.failteromhat.com Failte Romhat has lots of other useful links you could try looking at. Many of these are records particular to Cork.
Civil registration records are available from the General Register Office (GRO). These start from 1864 however. You can access the website here: http://www.groireland.ie/research.htm
Have you tried checking the Ellis Island records (www.ellisisland.org) or the Castle Garden records (www.castlegarden.org)? Generally, more information was given at the port of arrival rather than the port of departure. If you knew which city they arrived at, this could be a good place to find more information, and perhaps even find out an exact place of origin.
Please make sure you link anyone else in your family who is interested in their Irish heritage to our site - and indeed anyone else you know of Irish heritage.
Kind regards,
Sinead Cooney
Genealogist (Ireland XO)