《三国志·魏书·二公孙陶四张传》
黄巾军起义的时候，张燕召集一帮少年做强盗，在山林间辗转出击，等到回到真定，队伍已经壮大到一万多人。
黄巾起，燕合聚少年为群盗，在山泽间转攻，还真定，众万馀人。
When the Yellow Turban Uprising broke out, Zhang Yan gathered a group of young men to form a bandit group, and they fought their way through the mountains and forests. When they returned to Zhending, their group had grown to more than 10,000 people.
<s>[INST] Kindly elucidate the central themes in this passage in English: 黄巾起，燕合聚少年为群盗，在山泽间转攻，还真定，众万馀人。 [/INST] When the Yellow Turban Uprising broke out, Zhang Yan gathered a group of young men to form a bandit group, and they fought their way through the mountains and forests. When they returned to Zhending, their group had grown to more than 10,000 people.</s>
Kindly elucidate the central themes in this passage in English: 黄巾起，燕合聚少年为群盗，在山泽间转攻，还真定，众万馀人。
user
When the Yellow Turban Uprising broke out, Zhang Yan gathered a group of young men to form a bandit group, and they fought their way through the mountains and forests. When they returned to Zhending, their group had grown to more than 10,000 people.
assistant