The arrival of Europeans to New Zealand starting from the 17th century brought enormous change to the Māori way of life. Māori people gradually adopted many aspects of Western society and culture. Initial relations between Māori and Europeans were largely amicable, and with the signing of the Treaty of Waitangi in 1840 the two cultures coexisted as part of a new British colony. Rising tensions over disputed land sales led to conflict in the 1860s. Social upheaval, decades of conflict and epidemics of introduced disease took a devastating toll on the Māori population, which went into a dramatic decline, but by the start of the 20th century the Māori population had begun to recover, and efforts were made to increase their standing in wider New Zealand society. Traditional Māori culture has enjoyed a revival, and a protest movement emerged in the 1960s advocating Māori issues.