It is an interesting point to make that the two-handed technique with cavalry lances did not arrive until meeting the Makedonians. The reason this seems unusual is that many of the cavalry units that fought in the style of the Makedonian Hetairoi were not depicted with shields, which it can be concluded that the efficiency of the charge was emphasized by weilding with two hands rather than one hand and a shield (common sense tells us that longer lances need to be supported by more than one hand). But the fact that this hasn't been in use (as you say) seems unusual in the East. Of course, the length of the lances in other parts of the world in EB's timeframe in some locations such as Western Europe seem to lack the lengthy spears. The reason some civillizations could have them such as the Iberians could be from Carthaginian influence, which would have had contact with the Greeks and Makedonians. But as for the East, it seems strange that the development hadn't been around before then, especially with the heavy emphasis of cavalry in the steepes. I would expect the Europa Barbarorum team has information regarding this, so I will not speculate any further as I lack the historical information needed for this discussion.