argument over a horse
... that an argument over a horse led to a law banning all black settlers from Oregon in 1844?
... that an <b id="mwAxI"><a class="mw-redirect" href="./Cockstock_Incident" id="mwAxM" rel="mw:WikiLink" title="Cockstock Incident">argument over a horse</a></b> led to a law banning all black settlers from <a href="./Oregon" id="mwAxQ" rel="mw:WikiLink" title="Oregon">Oregon</a> in 1844?