China

China, the oldest and most populated nation on Earth in the 20th century (DW: Four to Doomsday), was located in the continent of Asia.

History

Circa 5519 BC, Monarch abducted Lin Futu and other natives of China. (DW: Four to Doomsday)

The Venetian Marco Polo traveled throughout China as the then-emperor Kublai Khan would not permit him to leave and return home. In 1289, The Doctor, Ian Chesterton, Barbara Wright and Susan met him during his travels. (DW: Marco Polo)

Circa 1860, Magnus Greel arrived in China from the year 5000. Li H'sen Chang found him and, believing him to be the god Weng-Chiang, became his devoted follower. (DW: The Talons of Weng-Chiang) In an unrelated incident, five years later, The Doctor, Ian Chesterton, Barbara Wright and Vicki visited China. (PDA: The Eleventh Tiger)

Troopers from the Boxer Rebellion were kidnapped by the War Lords for use in their war games. (DW: The War Games)

In 1936, the Doctor joined Mao Tse-Tung on the Long March. (DW: The Mind of Evil) Mao would take control of the country thirteen years later.

In 1967, Fitz Kriener was taken to China by Red Army soldiers. (EDA: Revolution Man)

In the 1970s, China set General Cheng Teik as a delegate to the first World Peace Conference in London. He was killed by his aide, Chin Lee, who was under the control of The Master. (DW: The Mind of Evil) Perhaps as a result of this, China was very reluctant to participate in the second World Peace Conference until persuaded by Sir Reginald Styles. (DW: Day of the Daleks)

By the year 2009, China was part of the worldwide nuclear grid overseen by UNIT. An Osterhagen station was located there.

In 1997, the government of China officially took over control of the formerly independent region of Hong Kong. (DWU: Sympathy for the Devil)

Presumably this happened in the main universe as well.