Globular cluster age distributions in the MW from Kruijssen et al. (2019), split up according to their likely progenitors from Forbes (2020). The shown classifications are the MW, GSE, unassociated high-energy GCs (H-E), unassociated low-energy GCs (L-E, which was given the name Koala by Forbes 2020), the Helmi Streams (H99), Sequoia (Seq), and Sagittarius (Sag). The curves are smoothed by the measurement uncertainties, which are computed through a summation over normal distributions with the respective ages as the means and their uncertainties as the standard deviations. The shaded region between 8 Gyr and 11 Gyr indicates the estimated time of the GSE merger (Belokurov et al. 2018; Helmi et al. 2018).