I see that this is an allegory. Just as Israel could be said to be in God's garden or kingdom when they were walking with Him. When they were in idolatry they were cast out into bondage of other nations. Just as the king of Tyre is compared to Lucifer as being in the garden in another scripture.
Here's two quotes from the Treasury of Scriptural Knowledge, compliments of e-sword, on these verses.
v10 "Therefore: The allegory and its interpretation are here combined; and the Assyrian monarch, though already destroyed, is poetically addressed."
v5 "his height: The Assyrian king, to whom Pharaoh is compared, from his great power, extensive dominion, and the protection he afforded, resembled the spreading branches, thick shade, and high stature of a flourishing cedar on mount Lebanon. The fruitful lands of Assyria; the immense revenues he drew from vast multitudes in his extensive territories; his lucrative commerce, by the river Tigris, with the countries on the Indian ocean; and all the various sources of his wealth and prosperity, resembled the rivers and streams which cause the trees planted by them to grow and flourish exceedingly; and hence the empire and its head were exalted above all the kingdoms of the earth. Psa_37:35-36; Isa_10:8-14, Isa_36:4, Isa_36:18-19, Isa_37:11-13; Dan_4:11"