A Relic of the Empire

in the short story collection Neutron Star (1968, together with Neutron Star 1966, At the Core 1967, Flatlander 1968, Grendel, The Handicapped and The Soft Weapon)

Larry Niven implicitly joined hist two previous timelines (The Belter Series and Neutron Star/Ringworld) in the story A Relic of the Empire, in which the background elements of the Slaver civilization (introduced in World of Ptavvs, from the Belter series) was used as a plot element of a story in the faster-than-light setting. Roughly 300 years separates the timeline of the last stories of the early setting (which are set roughly between 2000 and 2350), from the earliest stories in the later Neutron Star/Ringworld setting (which are set in 2651 (Neutron Star) and later).