What is "tanhuma"

Midrash Tanhuma ( Hebrew: מדרש תנחומא) is the name given to three different collections of Pentateuch aggadot; two are extant, while the third is known only through citations. These midrashim, although bearing the name of R. Tanḥuma, must not be regarded as having been written or edited by him. They were so named merely because they consist partly of homilies originating with him (this being indicated by the introductory formula "Thus began R. Tanḥuma" or "Thus preached R. Tanḥuma") and partly of homilies by aggadic teachers who followed the style of R. Tanḥuma. It is possible that R. Tanḥuma himself preserved his homilies, and that his collection was used by the editors of the midrash. The three collections were edited at different times; they will, therefore, be treated in chronological order.