Simplify the following text for a Grade 6 native English-speaking person.
Original: His movement eventually acquired tens of thousands of supporters , was virulently opposed by Iran 's Shi ` a clergy , and was suppressed by the Iranian government leading to the persecution and killing of thousands of his followers , called BÃ bÃ s. In 1850 , at the age of thirty , the BÃ b was shot by a firing squad in TabrÃ z.
Simplified: BÃ bism became very large ; over ten thousand people believed in the BÃ b. The Shi ` a clergy , or leaders of Islam in Iran hated the BÃ b and tried to harm people who followed his religion . In 1850 a firing squad , or group of gunmen , shot the BÃ b in TabrÃ z , Iran .