Puzur-Sîn is not included in the Assyrian King List [http://oracc.museum.upenn.edu/riao/kinglists/assyriankinglist/index.html] (AKL) and is known from just one poorly preserved tablet found at Aššur (text no. 1). This Old Assyrian inscription records that Puzur-Sîn, a son of the otherwise unattested Aššur-bēl-šamê, deposed Asīnum [http://oracc.museum.upenn.edu/riao/rulersofassyria/index.html], a descendent of Samsī-Addu I [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/samsiaddui/index.html]. Puzur-Sîn denounced his political rival as "not of the flesh of [the city] Aššur" (la ší-ir [URU] ˹d˺a-šur) (text no. 1 [http://oracc.museum.upenn.edu/riao/Q005681/], 12'-13'), thus portraying Samsī-Addu I and his descendants as usurpers to the Assyrian throne and his own seizure of the throne as the return of legitimate, native authority.
As for this man's identity, J. Reade has suggested that Puzur-Sîn should be identified as Iptar-Sîn [http://oracc.museum.upenn.edu/riao/fromsamsiaddutomittanicilent18081364bc/belubanidynasty/iptarsin/index.html], the fifty-first ruler listed in the AKL.
Browse the RIAo Corpus [http://oracc.museum.upenn.edu/riao/pager/]
BM 115688. Grayson, ARRIM 3 p. 13
A badly-worn and difficult-to-read stone tablet discovered near the ziggurat of the Anu-Adad temple at Aššur bears an unusual fifty-four-line inscription of Puzur-Sîn, a ruler who is not included in extant copies of the Assyrian King List. The text, which is now in the British Museum (London) and which is divided into four columns, records that Puzur-Sîn ascended to power by deposing Asīnum, an otherwise unknown successor of Samsī-Addu I. It also commemorates the construction of a wall, which its royal narrator claimed had never been built before. As for the nature of the inscription, A.K. Grayson states: "The literary form of the text is unparalleled. The text seems to be an attempt to revert to the Old Assyrian of royal inscriptions before the time of Šamsī-Adad I."
Access the composite text [http://oracc.museum.upenn.edu/riao/Q005681/] of Puzur-Sîn 1.
Jamie Novotny & Poppy Tushingham
Jamie Novotny & Poppy Tushingham, 'Puzur-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/samsiaddudynasty/puzursin/]