Sigtrygg II Silkbeard Olafsson, was a Hiberno-Norse king of which location, of the Uí Ímair dynasty?
Sigtrygg Silkbeard Sigtrygg II Silkbeard Olafsson (also Sihtric, Sitric and Sitrick in Irish texts; or Sigtryg and Sigtryggr in Scandinavian texts) was a Hiberno-Norse king of Dublin (possibly AD 989–994; restored or began 995–1000; restored 1000 and abdicated 1036) of the Uí Ímair dynasty. He was caught up in the abortive Leinster revolt of 999–1000, after which he was forced to submit to the King of Munster, Brian Boru. His family also conducted a double marriage alliance with Boru, although he later realigned himself with the main leaders of the Leinster revolt of 1012–1014. He has a prominent role in the 12th-century Irish "Cogadh Gaedhil re Gallaibh" and the 13th century Icelandic "Njal's Saga", as the main Norse leader at the Battle of Clontarf in 1014.
Dùn an Achaidh Dùn an Achaidh, sometimes Anglicised as Dun Acha, is a dun located near the village of Acha on the Inner Hebridean island of Coll. It is considered the best preserved dun on the island. The site of Dùn an Achaidh is located at grid reference [ NM18335456] . According to local tradition, the dun was the stronghold of, and named after, the son of a Norse king. The early 20th century antiquary Erskine Beveridge considered it as one of the four most interesting fortifications on Coll (along with Dùn Anlaimh, Dùn Dubh, and Dùn Morbhaidh).