Made a Little While Lower than the Angels
From the very beginning, man was created as God's steward and vice-regent to exercise dominion under God's authority. Although Adam and his wife were created in God's image and "very good", they needed to grow in faith, maturity, and wisdom until God granted access to the tree of the knowledge of good and evil and the kingly authority that tree would bestow. The sin of Adam and Eve—rebelling against God's word and usurping authority prematurely—led to their expulsion from the garden, and angels (cherubs) were placed as guards at the entrance of the garden. In fact, the whole world was placed under the guardianship of angels—temporarily. The angels were to serve and watch over mankind until Adam's race came of age. The goal all along was for humanity to grow up into maturity and share in the glory of God by exercising wise dominion over the world (Ps. 8; Heb. 1-2).
Sons of God
Some of the angelic rulers given authority over the nations (later called "sons of god" or "gods"; cf. 1 Cor. 8:4-6) rebelled against God and entered into sacred covenants with sinful men and women so that their royal offspring were considered children of the gods (Gen. 6). God sent a worldwide flood to judge wicked humanity and to set the stage for His plan of redemption. Even after the Flood, the wicked descendants of Ham banded together to build a tower to heaven and make a name for themselves (Gen. 11). Gen. 10 records the descendants of Noah's three sons, which includes 70 named people groups (called the "Table of Nations") that were scattered across the earth by God.
Deut. 32:8-9 also suggests that this judgment included an assignment of an angelic guardian ("son of God") for each of the 70 peoples but that God chose Jacob as His own possession. Israel's distinct status as a priestly nation among the nations can be seen in the fact that Israel is not numbered among the 70 peoples in Gen. 10. Moreover, Yahweh set Israel apart as His own treasured possession and entered into covenant with them directly. At the same time, passages like Daniel 10 and Jude 9 seem to suggest that Michael was assigned as the chief angel over Israel.
The biblical data, corroborated by apocryphal sources such 1 & 3 Enoch, suggest that the 70 angelic rulers of the nations formed the "Divine Council" that we see in passages like Job 1-2, 1 Kings 22, Ps. 82, Ps. 89, etc. But just as kings were seen as earthly representatives of their angelic counterparts, Israel was setup as an earthly analogue of the Divine Council. The rule of angels was only temporary, and Israel was a prototype of the new humanity that would one day reach maturity and be seated as the new and permanent Divine Council. This can been seen at Mt. Sinai when Moses, Joshua, and the 70 elders ascend halfway up the mountain to feast in God's presence (Ex. 24:9-11). We get another glimpse of things to come when 70 of the elders were temporarily anointed as prophets (Num. 11:24-25). The company of 70 elders in Israel (later known as the Sanhedrin) continued to serve as an earthly representation of the angelic Council, which would eventually be replaced by human prophets.
Heaven and Earth
What does Scripture say about the relationship between these angelic powers and the earthly rulers of the nations? Apparently, many angels rebelled against God and led the people astray by corrupting human kings (Ps. 58:1). At the same time, the snippets of biblical evidence suggest that we should not assume some sort of rigid and fixed arrangement concerning the influence of the angelic powers upon their human counterparts. It appears that angels often serve to tempt or test kings and rulers and that the response of the king determines the sort of influence the angelic ruler may have. Sometimes God gives rebellious kings over to evil/lying spirits, and sometimes God shows mercy on humble rulers so that the angels come to their aid.
Probably the most notable example is that of Saul, from whom God departed and instead sent "evil" spirits to afflict Him (1 Sam. 18:10-12). Ahab is another rebellious king who was handed over to lying spirits for his refusal to heed God's word (1 Kgs. 22). King David himself was apparently tempted by Satan at God's instigation and failed the test with disastrous results wrought by the angel of the Lord (2 Sam. 24; 1 Chr. 21:1). Darius the Mede may very well be an example of a king who humbled himself before the Lord and received angelic assistance. The night that Daniel was in the lion's den, we are told that Darius spent night fasting, sleepless, and without any diversions. In what appears to be an act of faith, he rushes to the den at daybreak and inquires whether or not Daniel's God has rescued him. As it turns out, God had sent an angel to protect the prophet, who was unharmed by the beasts. Although history is filled with examples of arrogant tyrants who were turned over to demonic influence, examples could also be multiplied of pagan kings who were converted by Israelite prophets and experienced the blessings of God.
Angels and the Elements of the World
Gal. 3:19 and Heb. 1-2 describe how the Torah was given from God and put in place by angels, who erected a divinely sanctioned system of "elements" to prepare Israel for the coming of Christ. Israel was to serve as the channel through which God would bring His blessings to all nations. Paul indicates in Acts 17 that God's purpose in this arrangement of the nations was to divide humanity, therefore restraining man's capacity for evil, while also putting the nations under angelic tutors that they might eventually come to a knowledge of the one true God. The angels, which were most likely worshiped as false gods, were probably influential in the formation of societal boundaries and structures of purity, holiness, and sacrifice, which are called "elements of the world" by Paul.  This would explain the apparent personification of the elements, sometimes called "elemental spirits" (Gal. 4:4; Col. 2:18). Furthermore, the kings of the peoples were very often considered divine or at least representatives of the gods under which they ruled.
Triumphing over Rulers & Authorities
Because of the angelic influence on human kings and their peoples, God's judgment on a nation was always a judgment on the angels/false gods of that nation as well as their human representatives. The plagues on Egypt are a clear example of this. Early in the ministry of Jesus, we see very that many of the angelic powers and human leaders of Israel had rebelled against God. Things were so bad that Mary and Joseph had to flee to Egypt (of all places!) to escape a wicked king trying to murder baby boys. Moreover, Israel was infested with demons, including the synagogues. When Satan offered kingdoms of the world to Jesus, he really had some degree of authority over the nations (Eph. 2:2). Otherwise, it wouldn't have been much of a temptation. Jesus knew that the ends of the earth had been promised to Him (Ps. 2:7-9), but He also knew that the only way to defeat Satan was through His death, resurrection, and ascension. Jesus came proclaiming the year of Jubilee, in which the land—in this case the whole world—would be returned to its rightful owner (Lk. 4:16ff.; Is. 61:1-2). This is why the 72 disciples sent out by Jesus have success in casting out demons, prompting Jesus to exclaim that He saw Satan fall like lightning (Lk. 10:1-20).
In light of this, Paul speaks about Jesus' victory over the elements of the world as coincidental with His triumph over rulers and authorities (Col. 2:6-23). Jesus executed sinful flesh and dismantled the elements of the world through His ministry and death. In doing so, He took away the primary tools used by the rulers and authorities to maintain control. Furthermore, the Father exposed the impotence of rulers and authorities by raising Jesus from the dead, thus overturning their guilty verdict. Christian martyrdom is such a powerful political weapon because Christians have no fear of death, which is the ultimate weapon of a tyrant.
What about Ephesians 6?
If this view is generally accurate, what are we to make of Paul's statement that "we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places" (Eph. 6:12)? This verse seems to contradict the view previously described and the whole notion that Christ has conquered principalities and powers and has elevated the Church to cosmic dominion with Him to over the angels. God's enemies (and ours) are very often flesh and blood, but Paul's admonition reminds us that God's human enemies are never the ultimate enemy. They are often animated by and under bondage to spiritual forces of evil (2 Tim. 2:24-26). And these rulers and authorities have been definitively defeated. The church has been given the task of realizing in history the definitive victory of Christ on the cross until the final day when Christ will return to defeat the final enemy, death itself. Therefore, Paul can say with confidence that the rulers of this age are doomed to pass away (1 Cor. 2:6-8), because it is through the Church that the manifold wisdom of God is being made known to the rulers and authorities in the heavenly places (Eph. 3:7-10).
Missionaries and church planters throughout the centuries have attested to the fact that demonic spirits and pagan magic only have control over a people until the gospel is proclaimed and the church established among them. Or in the case of great empire like Rome, principalities and powers are gradually displaced as the leavening effect of the church pervades and transforms the culture (Matt. 13:31-33). So, in pagan cultures, partially-Christianized nations, and even "post-Christian" nations, there is a great extent to which the Church still wrestles against heavenly powers. This situation will continue to varying degrees in various places until the return of Christ. Until then, it is imperative that we take up the whole armor of God and wield the weapons of God: prayer, Scripture, singing, worship, mercy/service, etc. Unlike the armies of Israel's who could only conquer human foes, the holy war that church wages by the power of the Spirit is able to destroy strongholds and vanquish the kingdom of darkness (Matt. 16:18; 2 Cor. 10:4).
 "The knowledge of good and evil" is used as something of a technical term to describe royal authority to pass judgment (Gen. 31:24; 2 Sam. 14:17; 1 Kgs. 3:9).
 See Michael S. Heiser, "Deuteronomy 32:8 and the Sons of God," Bibliotheca Sacra 158 (January-March 2001): 52-74. A Divine Council of 70 angelic beings may very well have grown with the expansion of the peoples of the world. As David E. Stevens argues, the idea of territorial spirits bound to a specific geographical region is pagan and not biblical ("Daniel 10 and the Notion of Territorial Spirits," Bibliotheca Sacra 157 [October-December 2000]: 410-31).
 Stevens, "Daniel 10 and the Notion of Territorial Spirits"
 "The body of Moses" is certainly not Moses' corpse but the nation of Israel (cf. 1 Cor. 10:1-2).
 The text doesn't say explicitly that Darius prayed for Daniel, but 6:16 certainly suggests that he did. And, of course, Daniel was certainly praying too!
 See Peter J. Leithart, Delivered from the Elements of the World
 G.B. Caird, Principalities and Powers, p. 82.