We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within \sim 4 kpc of the Galactic centre .
Characterised by a chemical composition resembling those of low mass satellites of the Milky Way , this new inner Galaxy structure ( IGS ) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy .
We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way .
Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations , we estimate that the progenitor system had a stellar mass of \sim 5 \times 10 ^ { 8 } M _ { \odot } , or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system .
We find that the accreted : in situ ratio within our metal-poor ( [ Fe/H ] < –0.8 ) bulge sample is somewhere between 1:3 and 1:2 , confirming predictions of cosmological numerical simulations by various groups .