There is no information in the sources about the political relations of the Great Seljuk State and the Ghurid State until the period of Sultan Sanjar (512-552/1118-1157). In the years when Sanjar's power coincided, Melik Izzeddin Hosayn (493-541/1100-1146), Seyfeddin Surî (541-544/1146-1149), Bahaeddin Sam (544/1149) and Alaeddin Hosayn (544-556/ 1149-1161) came to power. The period of Sultan Sanjar, which is considered as the second bright period of the Great Seljuk State, covers a very important process. As a matter of fact, Sanjar, who made an effort to strengthen his dominance in the region since his tenure, succeeded in subordinating important states such as Ghaznavids and Ghurids in this direction. In order to fully understand the Seljuk-Ghurid relations, which constitute the subject of our study, it is necessary to consider the relations of the parties with the Ghaznavids. The Ghaznavids, whose dominance in Khorasan was shaken with the Dandanakan War of 432/1040, which was a turning point in the Seljuk-Ghaznavid relations and resulted in the establishment of the Seljuk State, managed to continue their sovereignty. However, on 510/1117, Sanjar entered the city of Ghazna, which had not been captured by any Seljuk sultan before. Thus, the Seljuks came to the position of deposed between the parties. On the other hand, Sanjar, who played a major role in the ascension of Bahram Shah (511- 552/1117-1157) to the throne of Ghazna, did not intervene in the foreign affairs of the Ghaznavids as long as he remained loyal to him. Ghurid-Ghaznavid relations became completely strained when Bahram Shah had Kutbuddin Mohamed killed. When the leader of the Ghur, Seyfeddin Surî, got the news that his brother was killed, he gathered a large army and took action on Ghazna. However, after a while, Bahram Shah, who had Seyfeddin killed, regained control over Ghazna. When Bahaeddin Sam, who wanted to avenge his two brothers, died on his way to Ghazna, the other brother Alaeddin Hosayn set out for revenge. Especially the city of Ghazna suffered great damage during the wars between Bahram Shah and Alaeddin. Sanjar, who did not interfere in the foreign affairs of the Ghaznavids, applied the same policy for the second natural state. For this reason, there was no direct intervention in the Ghaznavid-Ghurid relations. The Seljuk-Ghurid political relations first started when Melik Izzeddin Hosayn established positive relations with Sanjar. Izzeddin tried to show his loyalty to Sanjar with the gifts he sent every year. Despite all this, there is information in Hasan-ı Yezdî's book named Câmiʻu't-tevârîh-i Hasenî that the Ghur people revolted against Sanjar in 515/1121. Although this information should be approached with suspicion because it is not found in other sources, it is important in terms of shedding light on Seljuk-Ghurid relations. The most intense field of struggle between the parties was Herat. It is seen that the city, which changed hands frequently, fell into the hands of the Ghurids after the 536/1141 Katvan defeat. In 542/1147, Sanjar wanted to take the city back through his commanders, but he could not succeed. The ruler of Ghur, Alaeddin Hosayn Jahansuz, acted as an independent ruler after capturing the city of Ghazna. He did not send the tax he had to pay and acted in partnership with the former governor of Herat, Ali Çetri, and rebelled against Sanjar. All these reasons caused Sanjar to go on an expedition against the Ghurids. In our study, the Seljuk-Ghurid political relations and the relations of the parties with the Ghaznavids will be examined during the Sanjar period. In addition, the relations of the mentioned three states within the scope of subjectivity-subjugationand will be evaluated and correct results will be tried to be drawn. In addition, the reasons that prompted Sanjar on an expedition against the Ghurids and the analysis of the Nab War of 547/1152 between the parties and its results will be emphasized.