Great Seljuq Empire ended in 1194.
Great Seljuq Empire was created in 1037.
Muhammad I - Seljuq sultan - died in 1118.
Seljuq campaigns in the Aegean happened in 1081.
Toghrul III of Seljuq died in 1194.
Mahmud II of Great Seljuq died in 1131.
Modern-day Turkey, modern-day Kyrgyzstan, the Middle East, and the Arabian Peninsula all composed the Great Seljuq Empire, which existed 1000 years ago.
shahs
Seljuq himself.
Not empire
he foundhis empire in europe
The underlying premise of the question is incorrect. The Byzantine Empire never converted to Islam and Islam was, by and large, illegal within the Byzantine Empire for as long as it existed. The reason why the territory formerly controlled by the Byzantine Empire became Muslim-majority was because it was conquered by various Islamic States such as the Rashidun Caliphate, the Umayyad Caliphate, the Seljuq Turkish Empire, and the Ottoman Empire (which finished the job).