From Elite Wiki

The history of Onrira becoming the first TL14 world in Sector 1 in a mere 14 years seems a tad unlikely. It means that Ceesxe (TL15), Inera, Tianve & Xexedi also achieved their current TLs in the past decade or so.

Purist view: Perhaps a result of the war against the Thargons which also decimated GalCop? There was a war at Inera.

See Oolite timeline for both purist & syncretist versions.