These are the commandments and ordinances that G-d commanded the Israelites through Moses in the plains of Moab, by the Jordan River opposite Jericho.
Bamidbar. 36:13
Jericho is the first locale that Joshua conquered when the Israelites crossed into the Land of Israel.
Allegorically, transforming Canaan into the Land of Israel means transforming our bodies and animating souls into holy entities. In this context, Jericho, the preliminary conquest, alludes to the most external aspect of our bodies and animating souls, our means of expression: action, speech, and thought. The word Jericho means “scent,” and scent is an external aspect of our being, something that other people can readily sense.
Conquering our modes of expression is the key to ultimately sanctifying and transforming our emotions (alluded to by the seven nations of Canaan) and intellect (alluded to by the future conquest of the three nations of Transjordan), just as Jericho was the “key” fortress that “unlocked” the way into the Land of Israel.
The path toward spiritual growth and life therefore begins with learning how to exercise control over action, speech, and thought. From there, we can proceed to refining our emotions and intellect.