Bass Aijie (Pinyin dī yīn ài jié kè), also known as Harzak, is a Uyghur stringed instrument. In the Qing Dynasty, it was included in the Jiabu music. There are two kinds of Aijie musical instruments: one still retains the resonant strings, and the other has no resonant strings, and the latter one is commonly used.

Aijik speakers are hemispherical, and one side is covered with sheepskin. After the liberation, Aijie was improved, the strings were changed to four metal strings, and the volume was increased. In addition, a crescent-shaped piano seat is installed on the iron column at the bottom of the speaker, which is convenient to be fixed on the lap for playing. The timbre of Aijie is soft, beautiful and full of national characteristics. It is an important musical instrument for Uyghur national bands.

In the 1960s, the musicians of the Xinjiang Uygur Autonomous Region Song and Dance Troupe cooperated with the Uyghur musical instrument makers from the Urumqi Yitiboke Musical Instrument Factory to design and develop the bass Aijie. The appearance is the same as that of the midrange Aijie, the resonance box is significantly enlarged, the cello strings are used, and the cello bow is used. Its playing posture and method are the same as the cello, and it is used as a bass-pulled stringed instrument in the Xinjiang Uygur Autonomous Region ethnic band.