I'm going back to the tone changes in Zireen languages. One of the things I noticed about Simik tones is that there are fewer than the possible combinations of tones in two-syllable words. In fact, most of them have a high tone on one syllable and a low tone on the other. Some of the main exceptions can be explained by phonetic change -- e.g., after a long low falling tone, the second syllable has a LOW rising tone instead of a high rising tone if it's short. This could be a case of assimilation (one question is if this sort of assimilation is realistic). So I'm trying to reconstruct successively older versions of Simik; then I can work forward from Proto-Simik to create related languages. I'm not concerned right now with working out the relationships between Simik and Tenai, if they exist. They could be the result of borrowing. Originally it seemed that the earlier form of Simik (which I'm tentatively calling Sumig) had a kind of pitch accent system. Either syllable could be stressed, but the stressed syllable could be rising or falling. But languages with pitch accent systems generally seem to have some restrictions on tones depending on which syllable gets the stress (from my very limited knowledge of Serbo-Croatian and Greek). Now it seems that the unstressed syllable can also be either rising or falling. This explains most of the data, and the few exceptions can either be altered or explained as borrowings from other languages. So what I'm wondering now is whether Sumig originally had two tones (rising and falling), and the language somehow developed a distinction of stress (high and low) on top of that, or if it originally had a stress system, and the contour tones developed later. High/low distinctions in single-syllable words might have developed from shortened forms of two-syllable words. What I really ought to do is learn something about a number of tonal languages and try to figure out how the tone systems work. It may turn out that Simik is an unnatural system and needs to be altered in some way. I can't think of any languages that have only contour tones and no level tones. But beyond a few of the more common languages, like Chinese, Thai, Vietnamese, and Tibetan, it isn't easy to find good information on tonal languages, especially relating to how the tone systems develop over time. Thai is interesting because the writing system reflects an earlier stage of development (as is Tibetan). But it's not easy to see how the existing tones could have developed from the tones represented in the writing system.