The name Cluetau is known from the registers of San Antonio de Valero Mission in San Antonio. Seven register entries for the period 1719–35 refer to one adult female. In three of these entries no ethnic identity is recorded; in two entries the woman is identified as a Sana; and in the two remaining entries she is identified as a Cluetau. This ambiguity makes it difficult to establish that Cluetau denotes a firm ethnic identity. Presumably there actually was an Indian group designated by this name, but the name, or some recognizable variant of it, has never been found in other documents. J. R. Swanton suggested that the Cluetaus may have spoken the Coahuilteco language. As there is no pre-mission information on Cluetau location and language, this suggestion is misleading.