Malay here originate from Taiwan I heard.
Another theory says that Malays originate from Taiwan under the "Taiwan-down-the-Philippines" theory.
Sumerians? I don't think so.. no academic discussions thus far that have suggested Sumeria as a geographic origin of the Malays. Perhaps you confused between SUMERIA and SUMATRA!! Plenty of connections between Malays and SUMATRA ... but SUMERIA ... ah ah ... I better check the Code of Hammurabi to ascertain that!!
It has been well accepted that Malays originate from somewhere in China. The traditional Malay migration theory says that Malays originate from Yunnan which is now a part of modern China. Even the Yunnan theory has two versions: Yunnan-down-the Malay Peninsula theory and Yunnan-down the-Mekong theory. Another theory says that Malays originate from Taiwan under the "Taiwan-down-the-Philippines" theory.
According to the Yunnan-down-the Malay Peninsula theory, early Malays, also called Proto Malays ('Proto' means 'First') arrived in Peninsular Malaysia between 35,000 t0 10,000 years ago during the Mesolithic Age. When they arrived the Negritoes were already living in Peninsular Malaysia. The Proto Malays pushed the Negritoes into hills and mountains in the interior. The Negritoes were thought to come to Peninsular Malaysia from Africa under the "Out of Africa " theory between 60,000 to 35,000 years ago. The Negritoes also reach the Philippines. A second wave of Malays, called Deutero Malays ('Deutero' means 'second') arrived in Peninsular Malaysia between 10,000 to 5,000 years ago. The Deutero Malays later spread from Malay Peninsular to the Malay Archipelago (Indonesia, Philippines, East Timor, Brunei) and the Pacific.
Today the Deutero Malays have evolved racially into modern Malays that make up the majority populations of Malaysia, Indonesia, Brunei, Timor Leste, Philippines and Malagasy. Modern Malays of Southeast Asia have also intermarried in recent times with Arabs, Indian, Chinese, Spanish, other Europeans, etc.
The Negritoes have evolved into the Semang Orang Asli group of Peninsular Malaysia. The Semang is further divided ethnically into the Kintak, Kensiu, Lanoh, Jahai, Mandriq and Batiq tribes who are found mostly in northern Peninsular Malaysia states like Kedah and Perak. In Philippines, the Negritoes brecome the Aeta tribe. The Proto Malays of Peninsular Malaysia have evolved into the Orang Asli tribes of Temuan, Semelai, Jakun, Kanaq, Kuala, Seletar, Temiar, Semai, Semoq Beri, Jahut, Mah Meri and Che Wong.
Another Yunnan Malay migration theory stipulates that the Malays, both Proto and Deutero, migrated from Yunnan down the mighty Mekong River to Southeast Asia and elsewhere. Some of them settled in Indo-China to build up empires that include Funan and Chanpa. From Indo-China, they sailed to Peninsular Malaysia and elsewhere into Southeast Asia and the Pacific.
Whatever routes from Yunnan that they took, Malays later evolved into two major groups: Malayo and Polynesians. The 'Malayo' group is basically racially Malay that today comprises Indonesia, Malaysia, Philippines, Timor Leste, Brunei and Malagasy. Those that reach the Pacific islands become Polynesians .. but today they are both still called Malayo-Polynesians.
Sources:
http://en.wikipedia.org/wiki/Orang_Aslihttp://asiarecipe.com/phihistory.htmlhttp://en.wikipedia.org/wiki/Prehistoric_Malaysiahttp://www.sabrizain.demon.co.uk/malaya/malays.htm