Read this and answer the question

The Punjabi kingdom, ruled by members of the Sikh religion, was a political entity that governed the region of modern-day Punjab. The empire, based around the Punjab region, existed from 1799 to 1849. It was forged, on the foundations of the Khalsa, under the leadership of Maharaja Ranjit Singh (1780–1839) from an array of autonomous Punjabi Misls. He consolidated many parts of northern India into a kingdom. He primarily used his highly disciplined Sikh army that he trained and equipped to be the equal of a European force. Ranjit Singh proved himself to be a master strategist and selected well qualified generals for his army. In stages, he added the central Punjab, the provinces of Multan and Kashmir, the Peshawar Valley, and the Derajat to his kingdom. This came in the face of the powerful British East India Company. At its peak, in the 19th century, the empire extended from the Khyber Pass in the west, to Kashmir in the north, to Sindh in the south, running along Sutlej river to Himachal in the east. This was among the last areas of the subcontinent to be conquered by the British. The first Anglo-Sikh war and second Anglo-Sikh war marked the downfall of the Sikh Empire.

Followers what religion were the rulers of the Punjabi Kingdom?
Sikh religion