One of the apocryphal books, the Psalms of Solomon is a group of eighteen psalms (religious songs or poems) written in the first and/or second centuries BCE that are not part of any current scriptural canon (they are, however, found in copies of the Peshitta and the Septuagint).
The 17th of the 18 psalms is similar to Psalm 72 which has traditionally been attributed to Solomon, and hence may be the reason that the Psalms of Solomon have their name. An alternate theory is that the psalms were so highly regarded that Solomon's name was attached to them to keep them from being ignored or forgotten.
The Psalms of Solomon were referenced in early Christian writings, but lost to later generations until a Greek manuscript was rediscovered in the 17th century. There are currently eight known 11th- to 15th-century manuscripts of a Greek translation from a lost Hebrew or Aramaic original, probably dating from the 1st or 2nd century BCE. However, though now a collection, they were originally separate, written by different people in different periods.
Politically, the Psalms of Solomon are anti-Hasmonean, and some psalms in the collection show a clear awareness of the Roman conquest of Jerusalem under Pompey in 63 BCE, metaphorically treating him as a dragon who had been sent by God to punish the Hasmoneans. Some of the psalms are messianic, in the Jewish sense (clearly referring to a mortal that happens to be divinely assisted, much like Moses), but the majority are concerned less with the world at large, and more with individual behavior, expressing a belief that repentance for unintended sins will return them to God's favor.
There have been attempts to link the text both to the Essenes of Qumran, who separated themselves from what they saw as a wicked world, and alternately to the Pharisees in opposition to the Sadducees who generally supported the Maccabees.