1917-1920 several independent Ukrainian states emerge on the territory of the former Russian empire but none of these states survive for long.
In 1922 the Ukrainian Soviet Socialist Republic (the Ukrainian SSR) is officially united with the USSR.
On 26 April 1986 a reactor explodes in the nuclear power plant of Chernobyl, causing a nuclear disaster.
On 16 June 1990 the Ukrainian SSR declares its sovereignty and neutrality.
On 24 August 1990 the Ukrainian parliament adopts the declaration of independence; Ukraine thus becomes an independent and democratic state.
In December 1991 Leonid Kravchuk is elected the president; on a referendum an overwhelming majority votes for independence. Ukraine joins the Commonwealth of Independent States.
In November 2004 – January 2005 the so-called Orange Revolution takes place in Ukraine. This is a wave of protests triggered by the forging of the election results (prime minister Viktor Yanukovych won the elections). Viktor Yushchenko, the leader of the opposition, challenged the results and won the support of large section of the population. The revolution brings Viktor Yushchenko and Yulia Tymoshenko to power.