Info from Wikipedia hymns
Ancient hymns include the Egyptian Great Hymn to the Aten, composed by Pharaoh Akhenaten; the Vedas, a collection of hymns in the tradition of Hinduism; and the Psalms, a collection of songs from Judaism. The Western tradition of hymnody begins with the Homeric Hymns, a collection of ancient Greek hymns, the oldest of which were written in the 7th century BC, praising deities of the ancient Greek religions. Surviving from the 3rd century BC is a collection of six literary hymns (yμνοι) by the Alexandrian poet Callimachus.
Patristic writers began applying the term yμνος, or hymnus in Latin, to Christian songs of praise, and frequently used the word as a synonym for “psalm”. 
Originally modeled on the Psalms and other poetic passages (commonly referred to as “canticles”) in the Scriptures, Christian hymns are generally directed as praise to the monotheistic God. Many refer to Jesus Christ either directly or indirectly.