Notes on the Bible, by Albert Barnes, , at sacred-texts.com
A tribute - Perhaps an allusion to some fresh arrangement of the tribute likely to have followed on the return of Xerxes from Greece.
Upon the isles of the sea - Cyprus, Aradus, the island of Tyre, Platea, etc., remained in the hands of the Persians after the victories of the Greeks, and may be the "isles" here intended.
Power and ... might - In the later years of Xerxes his "power and might" were chiefly shown in the erection of magnificent buildings, more especially at Persepolis. He abstained from military expeditions.
Kings of Media and Persia - Media takes precedence of Persia because the kingdom of Media had preceded that of Persia, and in the "book of the Chronicles" its history came first.
Mordecai ... was next unto king Ahasuerus - See Est 2:5 note. Artabanus (Est 1:14 note) was favorite toward the end of Xerxes' reign, i. e. in his 20th and 21st years.