A number of authors of the modern era, including Alison Sheridan and Robert Hensey, have attempted to categorise passage tombs.
This category may have distinctive abstract carvings or petroglyphs in the style of the Irish passage tomb tradition, solar alignments, recumbent kerbs.
These are constructed on a greater scale, possess more elaborate artwork and are architecturally extravagant, incorporating techniques such as corbelling (this is also seen in the second category), long roofed passages, sillstones, and with building materials brought from distant locations.
For instance at Carrowkeel, Sligo, a smaller cluster in the Bricklieve Mountains has a number of outlying sites such as the Pinnacle on Keash Hill, Ardloy, Heapstown and Suigh Lughaidh[5] One feature of Irish passage tombs that distinguishes them from other monumental types of the Neolithic era is the longevity of the tradition.
Ancient DNA research has associated the dead in the Irish monuments with early farming migrations to the Atlantic region about 6000 years ago.
Lara Cassidy stated, "It seems what we have here is a powerful extended kin-group, who had access to elite burial sites in many regions of the island for at least half a millennium".