Iptar-Sîn (written IB.TAR-d30; see Brinkman 1976-80, 23) is the fifty-first Assyrian king listed in the Assyrian King List [http://oracc.museum.upenn.edu/riao/kinglists/assyriankinglist/index.html] (AKL). His name is preserved only in the Khorsabad List [http://oracc.museum.upenn.edu/riao/kinglists/assyriankinglist/khorsabadlist/index.html]; it is assumed that it was also included in the SDAS List [http://oracc.museum.upenn.edu/riao/kinglists/assyriankinglist/sdaslist/index.html], but the lines mentioning his name are only partially preserved. Iptar-Sîn is said to have ruled for twelve years. He was a direct descendent of Bēlu-bāni [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/belubanidynasty/belubani/index.html] and, thus, a member of the "Bēlu-bāni Dynasty". He succeeded Šarma-Adad I [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/belubanidynasty/sharmaadadi/index.html], who is said to have been his father; he was succeeded by Bāzāyu [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/belubanidynasty/bazayu/index.html], who is described as being a son of Bēlu-bāni. B. Landsberger (1954, 42) suggests that Iptar-Sîn and his two immediate predecessors (Libāya [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/belubanidynasty/libaya/index.html] and Šarma-Adad I [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/belubanidynasty/sharmaadadi/index.html]) were Bēlu-bāni's brothers. Landsberger bases his argument on the supposition that the reign lengths in the AKL are not sufficiently long for each of these kings to have been sons of the Bēlu-bāni.
No surviving royal inscriptions are attributed to Iptar-Sîn. However, J. Reade (2001, 7) suggests that the AKL entry "IB.TAR-Sîn" may in fact be the result of a later misreading of the name "Puzur-Sîn" and, thus, Iptar-Sîn and Puzur-Sîn [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/samsiaddudynasty/puzursin/index.html], a monarch for whom one royal inscription survives, are one and the same man. If this hypothesis is to be accepted, it would imply that Iptar-Sîn's genealogy as given in the Khorsabad List is also incorrect, as Puzur-Sîn claims to be the son of the otherwise unattested Aššur-bēl-šamê.
Poppy Tushingham
Poppy Tushingham, 'Iptar-Sîn', The Royal Inscriptions of Assyria online (RIAo) Project, The RIAo Project, a sub-project of MOCCI, 2021 [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/belubanidynasty/iptarsin/]