It is utter ignorance to say that there were no knights in Poland. First of all, you need to separate the idea of knightly or chivalric culture/conduct from the function of knighthood (i.e. heavily-armed, usually mounted noble warrior caste, members of which were usually granted fiefs in exchange for military service, though not always).
Chivalric culture -- and this includes the oral and written poetry of the time -- was widespread throughout Latin Christian Europe. And Poland was firmly part of the Latin Christian culture of the Middle Ages. Yes, chivalry originated in Francia. Does that mean there were no knights in England? How about Scotland? Or Spain? Or even eastern Germany, which was never part of Charlemagne's empire? Of course not, because it spread throughout the Latin Christian cultural space. This space was not homogenous, but it was coherent in that it shared many of the same broad characteristics, notably fidelity to the Roman Church (and the many things that came along with it, like Latin as a language of learning and the religious orders). Further, there was considerable variation within regions which we would think of as definitely a part of the 'Feudal Western Europe'; this includes everything from liturgy, to landholding customs, and indeed 'knighthood'. Even if we take 'France' -- in many ways the archetype of feudal Europe -- the northern and eastern regions like Ile de France or Champagne would differ notably from the southern, like Toulouse, Aquitaine, and Languedoc. So Poland being different from its neighbours is not an argument for its separation from the broader Latin Christendom, because the latter was far from homogenous.
As for the practical function of Polish knighthood, there would doubtless be regional peculiarities, but no more so than in any other region in Latin Christendom. In essence, the practical characteristics are all broadly the same: heavily armed nobles, fighting on horseback, and usually in exchange for fiefs (or as direct retainers).
Now, most importantly, Edelfred seems to be confusing chivalric culture with the practical reality of knighthood. Yes, the knightly 'class' did subscribe to chivalric culture and its ideals. However, there were always cases of knights not living up to this ideal, and this is by no means unique to Poland. So to say that the Polish ambush in Galich was 'unknightly' is to misunderstand the realities of European knighthood and chivalry as a whole.
The fact is that Polish knights were as much 'knights' as their German, French, English, Spanish, or any other Latin Christian counterparts.