Mahmud of Ghazni was a powerful ruler of the Ghaznavid Empire, which was centered in present-day Afghanistan and parts of Central Asia. He is well-known for his military campaigns in the Indian subcontinent, particularly in the regions of Peshawar and Punjab. To conquer and annex these territories, Mahmud of Ghazni had to defeat the Hindushahis, who were the ruling dynasty in the region at that time.

Who were the Hindushahis?
The Hindushahis were a dynasty that ruled over the Kabul Valley, Peshawar, and parts of Punjab from the 9th to the 10th century. They were known for their resistance against the Arab invasions during the early Islamic period. The Hindushahi rulers were mostly Hindu, and they successfully maintained their independence for several centuries.

Mahmud of Ghazni's campaigns
Mahmud of Ghazni launched numerous military campaigns into the Indian subcontinent between 1000 and 1027 AD. His primary objective was to plunder the wealth and resources of the region, as well as to spread Islam. These campaigns were also aimed at extending his empire and establishing his dominance over the region.

Conquest of Peshawar
Peshawar, located in present-day Pakistan, was one of the major cities targeted by Mahmud of Ghazni. In 1001 AD, Mahmud launched an attack on Peshawar and successfully defeated the Hindushahis, led by Jayapala. Jayapala was captured and imprisoned, and Mahmud established his control over the city.

Annexation of Punjab
After conquering Peshawar, Mahmud of Ghazni turned his attention towards Punjab. He launched several military campaigns into the region, defeating various local rulers and establishing his authority. One of his major victories was against the powerful ruler Anandapala of the Shahi dynasty, who controlled parts of Punjab. Mahmud defeated Anandapala in the Battle of Waihind in 1008 AD, after which he captured and annexed Punjab.

Conclusion
In conclusion, Mahmud of Ghazni defeated the Hindushahis, led by Jayapala, to conquer and annex Peshawar. He also defeated Anandapala of the Shahi dynasty to establish his control over Punjab. These conquests played a significant role in expanding the Ghaznavid Empire's influence in the Indian subcontinent and laying the foundation for future Muslim invasions into the region.