Virtually nothing is known about Eric I of Gothenland, historians even argue about whether he was really Stenkil's son. However it is clear that when Stenkil died at some point in 1066, probably in the Spring, before Harald Hardrada's invasion of Anglia, Eric succeeded in getting the Gothenlandic lords' to accept him as their king.
He was probably young, at least younger than his brother Inge I who took Stenkil's Svealandic lands. This youth and inexperience possibly opened up court intrigue. Another Eric appears in the records, perhaps a member of one of the families Stenkil had displaced to become king. Their armies are said to have come to blows. The young king was dead by the end of the year.
With Eric now dead Sweyn II of Denmark promoted himself as playing on his good friendship with Stenkil. Gothenland would therefore fall into the Danish sphere for a generation.