អាណាចក្រហានត្រូវបានបែងចែកជាតំបន់ជាច្រើនដែល​គ្រប់គ្រងផ្ទាល់ដោយរដ្ឋបាលកណ្ដាលដែលគេស្គាល់ថាជាអាណាខេត្ត (តំបន់ដែនដីក្រោមការត្រួតត្រារបស់ប្រមុខខេត្ត, ភាសាចិន: 郡, ភិងអ៊ិង jùn, វ៉េដ–ហ្គែយល្ស៍ chün) និង​រាជាណាចក្រពាក់កណ្ដាលស្វយ័តជាច្រើន។ រាជាណាចក្រទាំងនេះបានបាត់បង់ឯករាជ្យរបស់ខ្លួនបន្តិចម្ដងៗ ជាពិសេសបន្ទាប់ពីចលនាបះបោរនៃនគរប្រាំពីរ។ The Xiongnu, a nomadic steppe confederation, defeated the Han in 200 BC and forced the Han to submit as a de facto inferior partner, but continued their raids on the Han borders. Emperor Wu of Han (r. 141–87 BC) launched several military campaigns against them. The ultimate Han victory in these wars eventually forced the Xiongnu to accept vassal status as Han tributaries. These campaigns expanded Han sovereignty into the Tarim Basin of Central Asia, divided the Xiongnu into two separate confederations, and helped establish the vast trade network known as the Silk Road, which reached as far as the Mediterranean world. The territories north of Han's borders were quickly overrun by the nomadic Xianbei confederation. Emperor Wu also launched successful military expeditions in the south, annexing Nanyue in 111 BC and Dian in 109 BC, and in the Korean Peninsula where the Xuantu and Lelang Commanderies were established in 108 BC.