Which region did the Turkish leader Seljuk conqure in establishing the first major Turkish empire in 1000?

The Turkish leader Seljuk established the first major Turkish empire by conquering the region of Persia, particularly the area around the city of Nishapur, in the 11th century. This expansion laid the foundation for the Great Seljuk Empire, which significantly influenced the political and cultural landscape of the Middle East. Their conquests included parts of modern-day Iran, Iraq, and beyond, marking the rise of Turkish power in the region.