Early European settlement in New Zealand was small, with only around 200 settlers by 1840, but increased rapidly after the Treaty of Waitangi established British sovereignty over New Zealand in 1840. Gold rushes in the 1860s attracted immigrants from outside Britain, particularly the United States and China. The largest wave of immigration came in the 1870s, when over 289,000 people arrived in New Zealand over 15 years. In the mid-20th century, many Pacific Islanders came for job opportunities, and more recently immigration has grown substantially from Asian countries like China and Korea.