These territories describe the same area. The list of territories can be included in the following sentence. Alternate translation: "In the territory of Zebulun and Naphtali ... in the territory of Galilee where many Gentiles live, the people who sat"
# The people who sat in darkness have seen a great light
Here "darkness" is a metaphor for not knowing the truth about God. And "light" is a metaphor for God's true message that saves people from their sin. (See: [[rc://en/ta/man/translate/figs-metaphor]])
# to those who sat in the region and shadow of death, upon them has a light arisen
This basically has the same meaning as the first part of the sentence. Here "those who sat in the region and shadow of death" is a metaphor. It represents those who did not know God. These people were in danger of dying and being separated from God forever. (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-metaphor]])