Viestards (also "Viesthard, Vesthardus, Viesturs") was one of the greatest Semigallian dukes in the 13th century, referred to as King Vester (Old High German: "konic Vesters" ).
 His capital was Tērvete hillfort.
 During the first decades of the 13th century he was allied with the Livonian Brothers of the Sword against Lithuanians, who looted Semigallia on several occasions.
 In 1205, joint forces of semigallians and crusaders defeated Lithuanians and killed duke Žvelgaitis.
Semigallians (Latvian "Zemgaļi"; Lithuanian: "Žiemgaliai" , also Zemgalians, Semigalls, Semigalians) were the Baltic tribe that lived in the southcentral part of contemporary Latvia and northern Lithuania.
 They are noted for their long resistance (1219–1290) against the German crusaders and Teutonic Knights during the Northern Crusades.
The Curonians or Kurs (Curonian: "Kursi"; German: "Kuren" ; Latvian: "kurši" ; Russian: курши ; Lithuanian: "kuršiai" ; Estonian: "kuralased" ; Polish: "Kurowie" ) were a Baltic tribe living on the shores of the Baltic Sea in what are now the western parts of Latvia and Lithuania from the 5th to the 16th centuries, when they merged with other Baltic tribes.
 They gave their name to the region of Courland ("Kurzeme"), and they spoke the Old Curonian language.
 Curonian lands were conquered by the Livonian Order in 1266 and they eventually merged with other Baltic tribes participating in the ethnogenesis of Lithuanians and Latvians.
 Direct descendants of the Curonians include the Kuršininkai of the Curonian Spit and the so-called Curonian Kings of Courland.
Scalovia (Lithuanian: "Skalva" , German: "Schalauen" ) was the area originally inhabited by the now extinct Baltic tribe of Skalvians or Scalovians (Lithuanian: "skalviai" , German: "Schalauer" ) which according to the "Chronicon terrae Prussiae" of Peter of Dusburg lived to the south of the Curonians, by the lower Memel (Nemunas) river, in the times around 1240.
Baltic Robinson: 2002, was the third version of "Expedition Robinson", or "Survivor" to air in the Baltic region of Europe.
 This season premiered on October 5, 2002 and aired until December 15, 2002.
 Like in the first two seasons, the three tribes were divided based on the contestants country of origin.
 Along with this, each tribe was given the name of the country of its contestants origin in that country's native language.
 As the first twist of the season, in episode one all three tribes were forced to vote out one member.
 What the contestants didn't know was that these three eliminated players would later return to the game after the merge in episode five.
 As there were twelve players in the merge tribe and three finalists, there was a nine-member jury.
 As each country had to be represented in the final three, contestant Ranno Rätsep became a finalist in episode eight when Maris Valdre, the only other remaining member of the Estonian tribe left in the game, was voted out.
 Because of this, Ranno was immune from the final elimination challenge in episode ten when all remaining Latvian and Lithuanian contestants had to compete against contestants from their home country for a spot in the final three.
 Ultimately, it was Rimas Valeikis of Lithuania who won the season with 4 votes against him, the runner up was Estonian Ranno Rätsep with 6 votes against him and the second runner up was Latvian Kristine Koļadina with 8 votes against her given by the jury.
Selonian was a Baltic language spoken by the Eastern Baltic tribe of the Selonians, who until the 15th century lived in Selonia, a territory in South Eastern Latvia and North Eastern Lithuania.
Yotvingia or Sudovia (Lithuanian: "Jotvingiai" , Old Prussian: "Sudawa", Polish: "Jaćwież" , Eastern Slavic: Яцьвезь (Ятвязь, Етвязь), Ятвягия) was a region where the Baltic tribe known as Yotvingians lived.
 It was located in the area of Sudovia and Dainava; south west from the upper Neman, between Marijampolė, Merkinė (Lithuania), Slonim, Kobryn (Belarus), Białystok, and Ełk (Poland).
The Scalovians (Lithuanian: "Skalviai" ; German: "Schalauer" ), also known as the Skalvians, "Schalwen" and "Schalmen", were a Baltic tribe related to the Prussians.
 According to the "Chronicon terrae Prussiae" of Peter of Dusburg, the now extinct Scalovians inhabited the land of Scalovia south of the Curonians and Samogitians, by the lower Neman River ca. 1240.
The Curonian language (German: "Kurisch" ; Latvian: "kuršu valoda" ; Lithuanian: "kuršių kalba" ), or Old Curonian, is a nearly unattested extinct language spoken by the Curonians, a Baltic tribe who inhabited the Courland Peninsula (now western Latvia) and the nearby Baltic shore.
 Curonian was a Baltic language; some scholars consider it to have been an Eastern Baltic, intermediate between Lithuanian and Latvian, while others like Vytautas Mažiulis classify it as Western Baltic.
Latgalians, sometimes also Ancient Latvians (Latin: "Lethi, Letthigalli" , Low German: "Letti, Lethi" , modern Latvian: "latgaļi, letgaļi, leti" , variant translations also include Latgallians, Lettigalls or Lettigallians) were an ancient Baltic tribe.

Question: What is the name of the Baltic tribe duke known as King Vester?
Answer: Viestards