  The Milky Way nuclear star cluster (NSC) is located within the nuclear
stellar disc (NSD) in the Galactic centre. It is not fully understood if the
formation and evolution of these two components are connected, and how they
influence each other. We study the stellar populations in the transition region
of NSC and NSD. We observed two $\sim$4.3 pc$^2$ fields with the integral-field
spectrograph KMOS (VLT), located at r$\sim$20 pc (> 4 R$_e$) to the Galactic
East and West of the NSC. We extract and analyse medium-resolution stellar
spectra of >200 stars per field. The data contain in total nine young star
candidates. We use stellar photometry to estimate the stellar masses, effective
temperatures, and spectral types of the young stars. The stars are consistent
with an age of 4-6 Myr, they may have formed inside the Quintuplet cluster, but
were dispersed in dynamical interactions. Most stars in the two fields are red
giant stars, and we measure their stellar metallicities [M/H] using full
spectral fitting. We compare our [M/H] distributions to the NSC and NSD, using
data from the literature, and find that the overall metallicity decreases from
the central NSC, over the transition region, to the NSD. The steep decrease of
[M/H] from the NSC to the region dominated by the NSD indicates that the two
components have distinct stellar populations and formation histories.
