'''Istemi''' (or '''Dizabul'''<ref>Howard, Michael C., ''Transnationalism in Ancient and Medieval Societies, the Role of Cross Border Trade and Travel'', McFarland & Company, 2012, p. 133.</ref> or '''Ishtemi Sir Yabghu Khagan''';<ref>Christoph Baumer, History of Central Asia, volume two, 2014</ref> {{zh|t=室點密}})
was the ruler of the western part of the [[Göktürks]], which became the [[Western Turkic Khaganate]] and dominated the [[Sogdiana|Sogdian]]s.<ref name=wood>{{cite book
| first=Francis
| last=Wood
| year=2002
| title=The Silk Road: Two Thousand Years in the Heart of Asia
}}</ref> He was the yabgu (vassal) of his brother [[Bumin Qaghan]] in 552 AD.<ref name="MichaelKappler2009">{{cite book|author1=Michalis N. Michael|author2=Matthias Kappler|author3=Eftihios Gavriel|title=Archivum Ottomanicum|url=https://books.google.com/books?id=SjwMAQAAMAAJ&q=mentioned+brother|year=2009|publisher=Mouton.|pages=68, 69}}</ref> He was posthumously referred to as khagan in Turkic sources.<ref>{{Cite web|url=http://bitig.org/?lang=e&mod=1&tid=1&oid=15&m=1|title=TURK BITIG|website=bitig.org|access-date=2018-07-28}}</ref> His son was [[Tardu]].