[dijit]

There aren't many examples of Unification, but there are examples, maybe this wouldn't be considered one of them.

My home country for instance is the "United Kingdom" which is made of up of countries/territories that unified many hundreds of years ago.

There's other examples such as the formation of Italy: https://en.wikipedia.org/wiki/Italian_unification

However, if it's not annexation it's probably better described as "ceding"; an American example: France ceded Louisiana to the United States by the treaty of Paris, of April 30, 1803. Spain made a cession of East and West Florida by the treaty of February 22, 1819.

Cessions have been severally made of a part of their territory by New York, Virginia, Massachusetts, Connecticut, South Carolina, North Carolina, and Georgia.

[galangalalgol]

unified is a proper term perhaps but at the time the gaelic speaking peoples would have probably used conquered or maybe colonized.

[dijit]

This is not an appreciable understanding of history. If talking about the UK specifically.