the need for a mid-winter feast lay in the fact that some of the provisions that the guy at the top of the hill, the overlord, had stashed in the summer and fall began to spoil by then, and so, the overlord would invite the folks at the bottom of the hill up for a grog and to fill their bellies (and pockets, I imagine) before the stuff went bad or the rats got it. This helped cement the relationship that he had with the folks at the bottom of the hill, who tended his fields, defended them from marauders, and served in his army.

That's one story behind the common seasonal holidays, irrespective of religious or ethnic association.

I've heard numerous assertions that the birth of Jesus couldn't have coincided with the winter solstice, as shepherds don't tend their flocks in the winter, since they're not out grazing at that time of year. Caesar Augustus wouldn't have wanted to tax the people in mid-winter, but, rather, would have wanted to count 'em during the time when they were most productive and least likely to move about. I don't know ... that was before my time.

RE