Nyland and Tavastehus County, Nylands och Tavastehus län or Uudenmaan ja Hämeen lääni, was a County of Sweden from 1634 to 1808, named after Nyland and Tavastehus. After the Treaty of Fredrikshamn in 1808 it continued to be a County of Finland until 1831 when it was split into Nyland County and Tavastehus County respectively. These became part of the Province of Southern Finland in 1997