i simply think that as organizations, Pride opened its gates to lots of international fighters to early on endeavor to find who the best fighters are in the world.. they were able to bring in Olympic gold medallists, International Kick boxing champions, Judo and Sambo world champions, ADCC champs, World BJJ champs etc etc.
the early financial troubles of the UFC, plus its early problems against US Senators for being a barbaric sport, led to a situation wherein it had limited funding to bring in and adequately pay international world class fighters and had to be happy with local talent who they dont need to pay much.. hence they also did events in small arenas whereas k-1 and pride were fighting in superdomes...
but times have changed, zuffa and dana white's sport management enterprises have breathed new life and infused big money into the UFC, blowing it up to a level where it is today.. and thus with high gate attendance at its events and amazing pay per view numbers, it can now afford to get the international caliber fighters that other organizations once had..
this is evidenced by the fact that even in its early years, Pride has had multiple countries holding its belts, the brazilians, the japanese, the russians, the americans because they saw the skill level on a worldwide level..
early in its life, the UFC only had american champs.. this has changed along the way though.. We see that Silva, a brazilian is now a force to be reckoned with in the UFC..
All in all, the UFC is on its way to great things when it finally understood that it should get international caliber fighters the way pride, K-1 and other organizations did..