We suggest two scenarios to explain the observations: First, is chemical enrichment over long time-scales in a galaxy which has experienced significant mass-loss during its evolution. The second possibility is that we are seeing the products of chemical enrichment from a system which experienced a large burst of star-formation, followed by a quiescent period of many Gyr. Both of these scenarios can lead to the situation where newly synthesized material from AGB stars and type Ia SN overwhelms nucleosynthesis products from a minor population of young, metal-rich, stars. It is likely that both mechanisms operate in the Sgr dSph.

Since these conditions should be generally applicable to low-mass systems, we expect to find similar abundance patterns in other dwarf galaxies. This is supported by the chemical composition of stars in the Galactic globular cluster ω Cen and in the Fornax dwarf galaxy, suggesting that both shared a history similar to the Sagittarius dwarf spheroidal galaxy.