Ya'aqov's (Jacob) son, Issachar, is generally placed with Zebulun when the twelves tribes of Israel are listed. This remains true in the last list of the twelves tribes in Hitgalut (Revelation) 7:4-8. Issachar's name means to hire or wages and comes from the Hebrew word sakar (שכר).

Bere’shiyt (Genesis) 30:18And Leah said, God hath given me my hire, because I have given my maiden to my husband: and she called his name Issachar.

The first appearance of this word is:

Bere’shiyt 15:1After these things the word of YHVH came unto Abram in a vision, saying, Fear not, Abram: I am thy shield, and thy exceeding great reward.

Issachar was prophesied by his father Ya'aqov in Bere’shiyt to be a bearer of burdens and a servant. The entirety of this chapter focuses on the future of the twelve tribes of Israel. Issachar's portion of the land is the area of Megiddo and Jezreel.

Shalom Alecheim!