The medieval city walls (named ‘Dış Kale duvarları’ = Walls of the Outer Castle) date from the 12th century, when Niksar was one of the capital cities of the Danışmend state. They are the third, the largest and youngest defence belt of the place, and had seven gates.
Danişmend = Turkmen dynasty that ruled in north-central and eastern Anatolia from 1080 to 1178. The dynasty centered originally around Sivas, Tokat, and Niksar; they extended as far west as Ankara and Kastamonu for a time, and as far south as Malatya, which they captured in 1103. In early 12th century, Danişmend were rivals of the Seljuk Sultanate of Rum, which controlled much of the territory surrounding the Danişmend lands, and they fought extensively with the Crusaders.

The dynasty was established by Emir Danişmend Gazi who took advantage of the dynastic struggles of the Seljuks upon the death of the Sultan Süleyman I of Rûm in 1086 to establish his own dynasty in central Anatolia. In 1100, Gazi's son, Emir Gazi Gümüştekin captured Bohemond I, Prince of Antioch, who remained in their captivity (in Niksar Castle) until 1103. A Seljuk-Danishmend alliance was also responsible for defeating the Crusade of 1101. Gümüshtigin died in 1134 and his son and successor Muhammed did not have the martial spirit of his father and grandfather. He is nevertheless considered the first builder of Kayseri as a Turkish city, despite his relatively short period of reign. When Muhammed died in 1142, the Danişmend lands were divided between his three brothers: Nizamettin Yağıbasan, who maintained the title of "Melik" (= King) and ruled in Sivas-Tokat-Niksar, Ayn Ud-Devle (who ruled in Malatya) and Zünnun (in Kayseri). They are known as ‘Üç Düşman Kardeş’ (Three Enemy Brothers); their rivalry weakened the Danişmend states.
In 1155, Seljuk Sultan Kılıç Arslan II attacked Melik Yağıbasan, who sought help from Nur ad-Din, the Zengid emir of Mosul. It worked, but when Nur ad-Din died in 1174, the Sivas lands were incorporated into the Rûm Sultanate. Four years later, the Malatya Danişmend (which had annexed Kayseri in the meanwhile) were defeated and also incorporated, marking the end of all Danişmend rule.

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Tokat’ (Ersal Yavi) – Tokat Otelcilik ve Turizm A.Ş. (1986) & Wikipedia.