31st century

The 31st century wasn't of particular interest to the Doctor, his companions, or even his enemies. According to Eldane, however, it was the time his branch of homo reptilia awakened from the slumber into which they placed themselves in 2020. It therefore was a time of renewed contact between his species and humans — although the precise details of that rapprochement were unclear. (DW: Cold Blood)

According to the Fifth Doctor, the 31st century was "all space cities and monorails." (BFA: The Butcher of Brisbane)