Deihan History, Family Crest & Coats of Arms
The ancient Gaelic form of the Irish name Deihan was O Dubhaigan. The first portion of the name is the word dubh, which means black; the second portion is likely some obsolete Irish personal name.
Early Origins of the Deihan family
The surname Deihan was first found in County Clare (Irish: An Clár) located on the west coast of Ireland in the province of Munster, where O'DuilAgin, O'Dugan, (or O'Deegan), chief of Muintir ConIochta, a district in the parish of Tomgraney, in the barony of Tullagh.
The family line is directly traceable to Fergus Mor (Fergus the Great). In turn his ancestry is associated with King Ir, brother of the equally famous Heremon. The name was first found near what is now the town of Fermoy, in the territory formerly known as Roche's Country. This territory encompassed the junction of the counties Cork, Tipperary and Waterford. In modern times, the surname is generally found in these three counties.
However, there was another O'Dugan sept in the territory called Ui Maine, also called Hy Many, which spans eastern county Galway and southern county Roscommon. This sept gave their name to the place called Ballyduggan, near Loughrea. 
Early History of the Deihan family
This web page shows only a small excerpt of our Deihan research. Another 155 words (11 lines of text) covering the years 1327, 1813, 1896, 1813, 1896, 1823 and 1884 are included under the topic Early Deihan History in all our PDF Extended History products and printed products wherever possible.
Deihan Spelling Variations
In the Middle Ages, a name was often recorded under several different spelling variations during the life of its bearer. Literacy was rare at that time and none of the languages to be found in the British Isles had achieved any great semblance of standardization. Variations of the name Deihan found include Dugan, Duggan, O'Duggan, Dougan, Douggan, Dewgan, Deugan and many more.
Early Notables of the Deihan family (pre 1700)
Another 29 words (2 lines of text) are included under the topic Early Deihan Notables in all our PDF Extended History products and printed products wherever possible.
Migration of the Deihan family
Irish families began to migrate to North America in the late 18th century in the hopes of gaining their own plot of land. The majority of these early immigrant families were relatively well off because the transatlantic passage was costly. As a result the decision to immigrate was carefully made. Those immigrants that arrived in the late 1840s differed because their decision to leave was in direct response to the Great Potato Famine. Many of the families that crossed the Atlantic during this decade were destitute, either having spent all they had on the fare or even starting with nothing, but being sponsored by a philanthropic society. Whenever, these Irish families came to North America, they were made great contributions to the developing nations of the United States and what would come to be known as Canada: the earlier settlers as land clearing homesteaders, and the later immigrants as the muscle that would build the industries and routes of transportation so critical to a powerful nation. Research into the passenger and immigration lists has shown many early and significant Irish immigrants bearing the name Deihan: James Dugan who settled in New York State in 1775; John Duggen, who arrived in Maryland in 1739; Cornelius Duggin, who arrived in Albany, NY in 1762; John Duggin, who came to Boston in 1765.