Re: The event, which
"The event, which celebrates its 30th anniversary, puts together two bull (male) camels with a female camel on heat nearby."
The words between the commas tell us more abouut the event. The commas act like brackets.
"The event which celebrates its 30th anniversary puts together two bull (male) camels with a female camel on heat nearby."
In that sentence, the words I have coloured red define the event. This is likely only if there are other events taking place, and these other events are not celebrating their 30th anniversary.
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