This paper provides a comprehensive examination of the seals of the so-called ‘Gulf Type’, which date to the end of the third millennium BC. It is argued that the Gulf Type seals are of key importance to our understanding of the origin of sealing and other administrative technologies within an emerging Early Dilmun ‘state’. Based on principal component analysis it is demonstrated that the shape of Gulf Type seals with inscriptions in Indus characters is distinct from seals without inscriptions. It is further argued that Gulf Type seals found in the Indus Valley, Iran, Mesopotamia/Bahrain and Bahrain can be connected with relatively discrete morphological groups apparently corresponding to different areas of production. The Indus inscriptions on the seals are investigated with particular emphasis on the abnormal occurrence of prefixed ‘twins’ signs in the western inscriptions. The hypothesis that a language different from that of the Harappans was used on these seals is reconfirmed on the basis of a newly found seal with a particular instructive pseudo-inscription. The paper concludes that breakaway Harappans operating in the western orbit invented the Gulf Type seals but that the type from around 2050 BC became practically synonymous with the merchant communities in Dilmun.