‘ This is the inheritance of the tribe of the children of Judah, according to their families.'
For this summary description with respect to the tribes compare Joshua 13:23 (Reuben); Joshua 13:28 (Gad); Joshua 15:20 (Judah); Joshua 16:8 (Ephraim); Joshua 18:28 (Benjamin); Joshua 19:8 (Simeon); Joshua 19:16 (Zebulun); Joshua 19:23 (Issachar); Joshua 19:31 (Asher); Joshua 19:39 (Naphtali); Joshua 19:48 (Dan). By this phrase the inheritance of each tribe was summed up.
It is noticeable that the portion of the half tribe of Manasseh in Transjordan was not described in this way but as ‘even for the half of the children of Machir according to their families' (Joshua 13:31), nor was the other part of Manasseh specifically so, although both did ‘inherit' - see Joshua 13:32; Joshua 16:9; Joshua 17:4. As the children of Joseph, Ephraim and Manasseh shared a joint inheritance (Joshua 16:4; Joshua 16:9; Joshua 17:14; compare Deuteronomy 34:2), even though it was in separate lots because they were so large (compare Joshua 14:4; Joshua 17:17). Ephraim also had possessions in the midst of Manasseh (Joshua 16:9). This in itself points to the early date of these records. In the Psalms (Psalms 60:7; Psalms 80:2; Psalms 108:8) Ephraim and Manasseh were totally separate tribes (but see 1 Chronicles 9:3). At this point Levi is still seen as the twelfth tribe, but with no inheritance apart from YHWH (Joshua 13:14; Joshua 13:33; Joshua 14:4), and gradually being replaced among the twelve by Manasseh (Joshua 14:4), who is not, however, at this stage a separate tribe inheriting.
This detailed description of the inheritance of Judah (and later of the other tribes) was seen as important because it demonstrated the fulfilment of God's promises to His people. He had promised them much land, they received much land. He had promised them cities to dwell in. They received cities to dwell in. Thus did they gain confidence and faith in the One Who fulfilled His promises. We too gain in confidence when we walk with God and receive His blessings. It gives confidence to go on to greater things.