关于'and,'的一个问题比如这句话when business was bad,Hawkwood and his men

关于'and,'的一个问题
比如这句话when business was bad,Hawkwood and his men would march into a city-state and,after burning down a few farms,would offer to go away if protection money was paid to them.这句话中的 'and,' 处为什么逗号在and的后面,而不是先逗号,再写and?
我想问的重点是，为什么是"and，" 而不是 " and" and不应该是跟着后面那句话的吗？