North Sumatra is well known for it's Batak Tribe,who claims North Sumatra as their homeland. While West Sumatra there is another ethnic group called Minangkabau people, who also claims that their ancestors were born on the Mount Merapi, near the town of Padang Panjang, close to Bukit Tinggi city. The term "Batak" is used to refer the original resident of North Sumatra. The areas referred to as their country is stretching from Medan up to the areas around lake Toba and further South in Mandailing regency, the border of West and North Sumatra.
Four sub-group is known for this Batak tribe those are Batak Karo, Batak Toba, Batak Mandailing, and Batak Simalungun. There is no physical and social differences, just a slight different in not visible behavior and dialect. Their different names refers the area where they live. Most of them are a Christian or Catholic, since around 18th century many Christian missionaries live in North Sumatra.
They also have Mongoloid characters, and speak Malayu- Polinesian language as the other part of Sumatra. Among them Toba was the latest area to open with other part of Sumatra, but soon getting so famous due to their natural beauty around Lake Toba with Samosir island on it. Historical remains of the Batak Toba in the past is still preserved well such as ancient king burial, slaughting altar, and the Tor Tor dance. These are all on the beach of Samosir island.
Now on the beach of Samosir island and across the lake called city of Parapat have been developing very fast as a tourists resort area with dozens of hotel small and big, nice roofed boats to cross the lake or sight seeing between island and places on the bank of the lake. The people of Batak is the resident of North Sumatra highland such as the present district of Tanah Karo, Simalungun, Tapanuli utara, Tapanuli Tengah, Tapanuli Selatan, Dairi and Ashan. More about the Batak.

The country of Minangkabau is the area now called West Sumatera with their capital is Padang city, located on the beach facing Indian Ocean. The area is divided into 3 administrative government at the level of 2 under the province. The unit customary organization of the people similar to a unit of a village which is called Nagari. Nagari is the total unit that bound their members on customs and life. It is estimated that the number of population is around 4.000.000. The people of Minangkabau used to leave their country and live at other areas of Indonesia, even in Malaysia. If you see a restaurant named "Ruman Makan Padang" it is a Minangkabau restaurant, and sometimes in short called "Rumah Makan Minang". Many experts say that matrilineal system of their society that force Minangkabau men to leave their land. Minangkabau people speak Malay with some silght different, which can be grouped as dialect /a/ tends to use /a/ as the first vowel, and dialect /o/ tends to use /o/ as the first vowel.
The original house of Minangkabau is a high house, built on poles with roofs shaped as horn, almost similar with that of Torajan in south Sulawesi. Thie house is called "Rumah Gadang" More about Minangkabau