The Asa is the collective noun given to the Norse pantheon and includes both the Aesir and the Vanir; the Asa are not merely synonymous with the Aesir. Moreover, the term Asa frequently has a much more religious connotation than the simple terms Aesir and Vanir, indicative of worship: it is the root of the contemporary re-implementation of pre-Christian Norse beliefs, Ásatrú. The membership of the gods to the Asa is often referred to directly within the Edda as, for example, Asa-Thor or Asa-Loki. The word "Asa" can also refer to a single male member of the Aesir.
See Norse mythology
Asa was king of Judah, the son of Abijam, and grandson of Rehoboam. Albright has dated his reign to 913 - 873 BC, while Thiele offers the dates 911 - 870 BC. 2 Chronicles describes his reign in a favorable manner; "He did what was good and right in the eyes of the Lord his God" (2 Chr. 14:2). Immediately after his accession to the throne he deprived his idolatrous mother Maachah of the title of Queen Mother (2 Chr. 15:16-18). He devoted his life to destroying idols and restoring the worship of Yahweh.
The first ten years of his reign were peaceful and he fortified Judah's cities. Then an army of Nubians (misleadingly called Ethiopians in 2 Chronicles) under the lead of Zerah (Osorkon II of Egypt) came upon him and Asa routed them, resulting in a peace with Egypt that lasted for the next three centuries (2 Chr. 14:9-15).
Then to the north King Baasha of Israel fortified Ramah on the border and declared war upon Judah (2 Chr. 16:1-6). Asa formed an alliance with King Benhadad of Damascus. A prophet told him that this alliance displeased the Lord, but Asa threw the prophet in prison (2 Chr. 16:7-10). Shortly after this, Asa contracted a disease in his feet and put no trust in the Lord, but in his physicians. On his death he was succeeded by his son Jehoshaphat (2 Chr. 16:12-14).