So did the Israelites. Bovine imagery was common in Semitic cultures after all (cf. the golden calf). In fact, as far as we can tell from artifacts, in folk Israelite/Judahite religion one of the ways Yhwh is portrayed in ‘graven images’ is as a bull / ox.
Bashan was known for its rich pastures - seriously, the land was fertile: abundant rainfall, volcanic soil - and cattle. It was a breadbasket. In the OT there are references to the “bulls of Bashan,” the “cows of Bashan,” (Amos 4:1) and the “fatlings of Bashan” (Ezekiel 39:18)
In connection with our LORD, maybe the Roman legions had a bull symbol of some kind?
There were no Roman legions in Judaea at the time. The nearest ones were up in Syria, and as far as we know, they never went to Judaea during Pilate’s ten-year prefecture. Pilate seems to have been able to deal with any trouble in the area using his own auxiliaries. That suggests that during the 30s, Judaea was still a relatively peaceful area. (That legions came down during the Jewish-Roman War thirty years later is an indicator of just how serious things had become by that time.)
In fact, the fact that Pilate managed to govern Judaea for ten years is a feat in itself. Many other governors before and after him only governed for 2-3 years on average. He is the second-longest governor.