10 most difficult South-East­ern Asia riddles

The waters of river are indeed reddish because of the large amounts of red silt.

The four largest cities in Indonesia are Jakarta (9.6 million), Surabaya (2.8 million), Bandung (2.6 million) and Bekasi (2.5 million).

Thailand borders Myanmar, Laos, Cambodia and Malaysia.

The four largest cities in Vietnam are Ho Chi Minh City (8.2 million), Ha Noi (7.4 million), Hai Phong (1.9 million) and Can Tho (1.2 million).

Indonesia borders Papua New Guinea, East Timor and Malaysia.

Aceh is located in the northern end of Sumatra, and the westernmost part of the whole Indonesia. Aceh is thought to have been the place where the spread of Islam in Indonesia began (in 1250). In the early seventeenth century the Sultanate of Aceh was wealthy and powerful.

The country has always been called Mueang Thai by its citizens. Portuguese explorers named it Siam, possibly from the Chinese name “Xiam”. The name “Siam” was used officially by Thai government until 1939, when it was changed to Thailand. In 1945 the name reverted to Siam, and in 1949 reverted once again to Thailand.

In 1989, the military government officially changed the English translations of many names dating back to Burma's colonial period or earlier, including that of the country itself: "Burma" became "Myanmar". Both these names are derived from the name of the majority Burmese Bamar ethnic group. Myanmar is considered to be the literary form of the name of the group, while Burma is derived from "Bamar", the colloquial form of the group's name.

Manila is the most densely populated city in the world, with 41,515 inhabitants per square kilometre.

Kalimantan is the Indonesian portion of the island of Borneo (73% of the whole island).