How is the jori related to the pakhawaj?

The jori is a vertical form of the pakhawaj: the barrel drum's two heads become two upright drums, with timbre and technique close to the pakhawaj and the left and right sides inverted. Sikh tradition credits Guru Arjan Dev with creating it from the older mridang or pakhawaj. Bhai Baldeep Singh uses the term jori-pakhawaj to separate it from the tabla.