In Numbers 32: 33 no reason is given why Moses decides to split the tribe of Manasseh that they settle together with the tribes of Gad and Reuben on the other side of the Jordan. It is because Manasseh is the anagram of Neshamah = soul.

The essence of the story is that man (Adam) only comes alive when the heavenly soul, the neshamah, joins with the bodily soul, nefesh (Genesis 2:7). He cannot live, and is not alive, without the neshamah, and without the neshamah he is no more than flesh and bones.

Whilst Joseph was the neshamah of the 12 twelve brothers, his two children Ephraim and Manasseh were the nefesh and the neshamah. Ephraim was the nefesh of the two and was more ‘dynamic’ and closer to earthly matters. It was for this reason that Jacob (Israel), in his blessing of the two sons, placed preference on Ephraim over Manasseh (Gen. 48:14) foreseeing the need for earthly action during the coming generations. Manasseh was the neshamah of the two brothers and after the passing of Joseph becomes the main link between the tribes of Israel and God. The name Manasseh spelled mem-nun-shin-heh מנשה  is an anagram of neshamah spelled nun-shin-mem-heh נשמה – it is also an anagram of the word ‘Mishnah’ mem-shin-nun-heh משנה – a systematic analysis of Jewish halachic laws.

We see the significance of the role of Manasseh in Numbers 32 where the tribes of Gad and Reuben pleaded with Moses not to cross the River Jordan to the Land of Canaan with the rest of the Children of Israel and to remain on the east side of the Jordan River because the pastures there are good for their herds.

The sons of Gad and the sons of Reuben came and spoke to Moses, and to Eleazar the priest, and to the princes of the congregation, saying……: Therefore, said they, if we have found grace in your sight, let this land be given to your servants for a possession, and bring us not over the Jordan (Num. 32: 2 and 5).

Moses agreed, but on the condition that half the tribe of Manasseh go with them:  

And Moses gave to them, to the sons of Gad, and to the sons of Reuben, and to half the tribe of Manasseh the son of Joseph, the kingdom of Sihon king of the Amorites, and the kingdom of Og king of Bashan, the land, with its cities in the borders, even the cities of the country around (Num. 32:33). No reason whatsoever is given in the Torah for this division of the tribe of Manasseh, whereby half the tribe lived on the east side of the Jordan River and the other half on the west with the other 10  tribes of Israel. But from the above analysis we can see that the tribe of Manasseh was the neshamah of Israel; it was the connecting force between the Children of Israel and God. Were the tribes of Gad and Reuben separated from the other tribes without the neshamah, they would surely dissolve into the tribal communities of the region. The splitting of the tribe of Manasseh effectively created a bridge of the neshamah between the nation of Israel, ensuring that the tribes of Gad and Reuben would be linked to God. Not only is man but also a nation is unable to live without the neshamah.

Moreover, both Manasseh and neshamah have the same Gematria =390 =shemayim = heaven meaning that the tribe of Manasseh are not only connecting the tribes of Gad and Reuben with teh other 10 tribes of Israel but also connecting Israel with Heaven. This did not happen when the tribes of Israel split into Judah and Benjamin and the 10 tribes after the death of Solomon (I Kings 12:12-21).

[1] The bridge of the neshamah created by the half tribe of Manasseh between the tribes of Gad and Reuven did not last more than a few generations for in I Chronicles 5 reads: 25. And they (half tribe of Manasseh) transgressed against the God of their fathers, and played the harlot after the gods of the peoples of the land, whom God destroyed before them: 26. And the God of Israel stirred up the spirit of Pul king of Assyria, and the spirit of Tilgath-Pilneser king of Assyria, and he carried them away, the Reubenites, and the Gadites, and the half tribe of Manasseh, and brought them to Halah, and Habor, and Hara, and to the river Gozan, till this day:.