1840s

thumb|335x335px|From top left, clockwise: The Mexican–American War ushers in the American expansion in its western frontier, paving way for new territories (and eventually states) such as [[Texas and California; the signing of the Treaty of Waitangi in 1840 guarantees continued Māori sovereignty but also leads to the proclamation of the nominal Colony of New Zealand; The great auk goes extinct, as it falls victim to overhunting; The First Opium War catalyzes Europe's imperial encroachment and control over Chinese ports, as the war resulted with Hong Kong's succession to Britain via the Treaty