Question: Where did the tribe inhabit that the electoral district was named after that include an outer southern suburb of Adelaide that lies within the City of Onkaparinga and has the postcode 5173?

Context paragraphs:
Chavakachcheri Electoral District: Chavakachcheri Electoral District was an electoral district of Sri Lanka between August 1947 and February 1989.  The district was named after the town of Chavakachcheri in Jaffna District, Northern Province.  Kilinochchi Electoral District was carved out of the southern part of the district in March 1960.  The 1978 Constitution of Sri Lanka introduced the proportional representation electoral system for electing members of Parliament.  The existing 160 mainly single-member electoral districts were replaced with 22 multi-member electoral districts. Chavakachcheri electoral district was replaced by the Jaffna multi-member electoral district at the 1989 general elections, the first under the PR system, though Chavakachcheri continues to be a polling division of the multi-member electoral district.

Port Willunga, South Australia: Port Willunga is a semi-rural suburb of Adelaide, South Australia.  It lies within the City of Onkaparinga and has postcode 5173.

Colombo West Electoral District: Colombo West electoral district was an electoral district of Sri Lanka between July 1977 and February 1989.  The district was named after the city of Colombo in Colombo District, Western Province.  The district was created by the division of the Colombo South Electoral District into Colombo East and Colombo West electoral districts in July 1977.  The 1978 Constitution of Sri Lanka introduced the proportional representation electoral system for electing members of Parliament.  The existing 160 mainly single-member electoral districts were replaced with 22 multi-member electoral districts. Colombo West electoral district was replaced by the Colombo multi-member electoral district at the 1989 general elections, the first under the PR system, though Colombo West continues to be a polling division of the multi-member electoral district.

Sellicks Beach, South Australia: Sellicks Beach is an outer southern suburb of Adelaide, South Australia which is located in the local government area of the City of Onkaparinga and is the southernmost extent of the Adelaide metropolitan area.  At the 2006 census , Sellicks Beach had a population of 2,339.

Aldinga Beach, South Australia: Aldinga Beach is an outer southern suburb of Adelaide, South Australia.  It lies within the City of Onkaparinga and has the postcode 5173.  At the 2011 census , Aldinga Beach had a population of 9,697.

Kilinochchi Electoral District: Kilinochchi Electoral District was an electoral district of Sri Lanka between March 1960 and February 1989.  The district was named after the town of Kilinochchi in Kilinochchi District, Northern Province.  The district was carved out of the southern part of Chavakacheri Electoral District in March 1960.  The 1978 Constitution of Sri Lanka introduced the proportional representation electoral system for electing members of Parliament.  The existing 160 mainly single-member electoral districts were replaced with 22 multi-member electoral districts. Kilinochchi electoral district was replaced by the Jaffna multi-member electoral district at the 1989 general elections, the first under the PR system, though Kilinochchi continues to be a polling division of the multi-member electoral district.

Electoral district of Mawson: Mawson is an electoral district of the House of Assembly in the Australian state of South Australia.  It covers most of the outer southern suburbs of the City of Onkaparinga, including Hackham, Hackham West, Huntfield Heights, Noarlunga Downs, Old Noarlunga, Onkaparinga Hills and Seaford Heights, the regional shopping centre area at Noarlunga Centre, parts of Woodcroft, and the southern wine region around McLaren Vale and Willunga.

Colombo East Electoral District: Colombo East electoral district was an electoral district of Sri Lanka between July 1977 and February 1989.  The district was named after the city of Colombo in Colombo District, Western Province.  The district was created by the division of the Colombo South Electoral District into Colombo East and Colombo West electoral districts in July 1977.  The 1978 Constitution of Sri Lanka introduced the proportional representation electoral system for electing members of Parliament.  The existing 160 mainly single-member electoral districts were replaced with 22 multi-member electoral districts. Colombo East electoral district was replaced by the Colombo multi-member electoral district at the 1989 general elections, the first under the PR system, though Colombo East continues to be a polling division of the multi-member electoral district.

Electoral district of Kaurna: Kaurna is an electoral district of the House of Assembly in the Australian state of South Australia.  Named after the Kaurna aboriginal tribe which originally inhabited the Adelaide plains, it is a 52.7 km² semi-urban electorate on Adelaide's far-southern beaches, taking in the suburbs of Aldinga Beach, Maslin Beach, Moana, Port Noarlunga, Port Noarlunga South, Port Willunga, Seaford, Seaford Meadows and Seaford Rise as well as parts of Aldinga and Christies Beach.  It is one of only two state districts named after South Australia's indigenous people (the other being the Electoral district of Narungga).

Electoral district of Heysen: Heysen is an electoral district of the House of Assembly in the Australian state of South Australia.  It is named after Sir Hans Heysen, a prominent South Australian landscape artist.  It is a 1,102 km² electoral district that takes in some of the outer southern suburbs of Adelaide before fanning south-east to include most of the Adelaide Hills, as well as farming areas some distance from the capital.  It includes the areas of Aldgate, Bridgewater, Echunga, Hahndorf, Macclesfield, Meadows, Stirling and Strathalbyn, as well as part of Mount Barker.  Although geographically it is a hybrid urban-rural seat, it is counted as a metropolitan seat.

Supporting paragraphs: Electoral district of Kaurna Aldinga Beach, South Australia
Answer: Adelaide plains