Origins of Batswana
The early history of the Tswana people was not written down but passed orally from generation to generation.
Many Batswana believe the Matsieng creation story; at a time when rocks were soft, Matsieng came from the underworld through a hole in the ground, bringing with him his people and wild and domestic animals, and leaving his one-legged footprints in the soft rock.
Apart from the Basarwa and Kalanga, most of the tribes in Botswana are descended from two groups, the Batswana and Bakgalagadi groups who were living in the Magaliesberg Mountains area in South Africa at the time of the Zimbabwe state.  Over time groups of people broke off from their parent tribe and moved to new land, creating new tribes and absorbing or subjugating the people they found. In this way the people evolved into the numerous Tswana tribes which exist today in Botswana, Lesotho and parts of South Africa.
The Bakaa split from the Barolong around 1450, and originally stayed near modern day Molepolole. The name Bakaa is thought to come from “Ba ka ya” meaning “They can depart”.
At about the same time the Bakwatheng broke away from the Barolong, also settling near Molepolole.  (Other sources suggest the Bakwatheng are from the Bakgalagadi group).  At some later point the Baphaleng split from the Bakwatheng and moved north to settle near Shoshong.
Having migrated to several places, around the early 1700’s a group of Bakaa under Kgosi Mmopane settled near the Shoshong hills. After paying tribute to the dominant Bakhurutshe tribe for three years, they rose up and subdued them.  The Bakaa became the dominant tribe in the area, but the Bakaa and Baphaleng have had a long history of peaceful coexistence, dating from before they were in Shoshong.
DifaqaneThe period from around 1700 until the 1840’s was a period of upheaval and turbulence for people in Southern Africa, culminating in the Difaqane or “Times of Trouble”. There were numerous causes including the Zulu warlords and later the arrival of white farmers from South Africa, but the net result was great instability and people being forced to move gradually northwards. 
Having split from the Bakwena group about four generations earlier, the Bangwato tribe came to the Shoshong area in around 1770 as refugees from the southern wars and settled at Mamutlhe. “The Bamangwato with their chief Mathibi fled to the north and took up their abode in the hills of Leshosho, better known today as Shoshong.”  The Bangwato may have been invited to Shoshong by the Baphaleng who fought alongside them against the Mashona a few years earlier. 
Kgosi Mathiba married a Mokwena woman and had a son Tawana before marrying his chief wife with whom he had a son Khama. Khama later attacked his half brother Tawana, who fled with his father and established the Batawana near to Lake Ngami (not far from modern day Maun). In the 1790’s Khama (I) became the kgosi of the Bangwato.
The Bangwato tribe moved frequently, and under the next kgosi, Kgari, they lived in Mabele-a-pudi, north of Serowe, for a period. Around 1826 a group of Kololo passed through the Shoshong area expelling the Bangwato, before carrying on northwards to the Boteti River and settling around the Chobe River in about 1835.
In 1832 Khama II became kgosi of the Bangwato, followed by Sekgoma who became kgosi in around 1835 shortly before the birth of his son Khama, in Mosu (near the Makgadikgadi pans). Around 1840 they moved to Pitsane Hill near Shoshong again fleeing attacks by the Matabele (Ndebele).
One of the first white travellers to reach the Shoshong area was David Hume who visited in 1832 and again in 1835, opening the way for more traders and hunters. 
Tribal Structure The people under his authority were the morafe. Important decisions in the village were taken in the kgotla. The kgosi would be assisted by doctors/diviners (dingaka) for spiritual leadership, providing rain, and preventing the influx of pests and plagues. The kgosi typically had several wives. Bogadi (bride wealth) was paid in cows (typically four to ten) which were given by the groom’s father and uncles to the family of the bride.
Conquered people and in particular the Basarwa were often badly treated, and used as servants.
VoortrekkersFrom around 1836 Afrikaner Voortrekkers or Boers started moving northwards into the Transvaal and southern and eastern parts of what is today Botswana. Some slave trading took place, though not as much as in other areas of Africa. Enterprising Batswana were able to trade and purchase guns, which had a significant effect in being able to resist would-be attackers over the next hundred years.
References[1,2,3,6] Tlou T & Campbell A (1997) “History of Botswana.” Macmillan
 Ramsey - Sunday Standard 2011-07-25.
 Parsons N (1973a) “On the Origins of the bamaNgwato.” Botswana Notes & Records Vol 5
 Parsons (1973a) as above - quoting from J.T Brown giving a Kwena viewpoint!
 Parsons N (1972) “Khama’s own Account of Himself.” Botswana Notes & Records Vol 4
 Campbell A & Main M (2003) “Guide to Greater Gaborone.” Published in association with The Botswana Society AND Sillery A (1965) “Founding a protectorate: history of Bechuanaland, 1885-1895” Mouton
 Morton F, Ramsey J & Mgadla PT (2008) “Historical Dictionary of Botswana“