It is also equivalent with Taiwan, Philippines, Singapore, Brunei, most of Mongolia, Malaysia, Irkutsk Time of Russia, Western Australia, and Central Indonesia.
By 1918, five standard time zones had been proposed by the Central Observatory of Beiyang government of Republic of China, including the Kunlun (UTC+05:30), Sinkiang-Tibet (UTC+06:00), Kansu-Szechwan (UTC+07:00), Chungyuan (UTC+08:00), and Changpai (UTC+08:30).
[citation needed] A further refined system with adjustment to zone assignment in the Northwest part of Gansu was announced in 1947 for adoption in 1948.
[3] In 1997 and 1999, Hong Kong and Macau were transferred to China from the United Kingdom and Portugal respectively, being established as special administrative regions.
Although the sovereignty of the SARs belongs to China, they retain their own policies regarding time zones for historical reasons.
As an illustration of the wide range, the daylight hours (Beijing Time) for the seats of the westernmost (both including and not including Xinjiang due to local customs, see below) and easternmost counties, calculated for the year 2010, are shown here:[5] The border with Afghanistan at the Wakhjir Pass has the most significant official change of clocks for any international land frontier: UTC+08:00 in China to UTC+04:30 in Afghanistan.
[3] The coexistence of two time zones within the same region causes some confusion among the local population, especially when inter-racial communication occurs.
[16] Regardless, Beijing Time users in Xinjiang usually schedule their daily activities two hours later than those who live in eastern China.
Before that, local time was determined by astronomical observations at Hong Kong Observatory using a 6-inch Lee Equatorial telescope and a 3-inch Transit Circle[clarify].