The Alaca Mescit was originally built in 1300, during the period the Rum Seljuk territory was administrated by a (Seljuk) vizier under ‘Ilhanlı’ supervision. In 1505 the little mosque was restored to honour the memory of the son of a Ahi, who had fallen in battle.
So, the prayer hall is mixed Seljuk-Ottoman, but the minaret is original. Its decorative brick pattern is striking; a cornerstone with a Seljuk inscription is inserted into its base. It is the second oldest minaret of Tokat, but much nicer dan the older one.

‘Mescit’ = little mosque, not suitable for the Friday prayer, because there is no minber/pulpit.
(Although: during the 20th century, a small, plain wooden minber was placed inside the Alaca Mescit, causing it to be called ‘Alaca Cami’ as well). (Cami = mosque).
‘Ilhanlı / Ilkhanids’ = the Iran based Mongols, who defeated the Seljuk at the Battle of Köse Dağ in 1243 and annexed their territory.
‘Ahi’ = member of an historically influential religious and commercial fraternity, founded by Ahi Evren (1169–1261).

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Türkye Tarihi Yerler Kılavuzu’ – M.Orhan Bayrak, Inkılâp Kitabevi, Istanbul, 1994 & Wikipedia.