A large proportion of the toli in museum collections were not made for the use they ended up serving. They are Chinese bronze mirrors, manufactured for domestic and funerary use over a very long period, traded north and east in quantity, and then drilled, looped and fitted to costumes by Buryat, Evenki, Daur and Manchu practitioners. Some are centuries older than the coats they hang on. Alongside them sit local castings that copy the imported form, and plain discs with no ornament at all.
That reuse is worth stating plainly, because the popular picture of Siberian practice is of something sealed off and archaic. It was not. These are trade goods, absorbed from a neighbouring empire and given a new job, and the same is true of the beads, coins, bells and iron fittings that appear alongside them. A costume assembled over a working life is a record of what its owner could obtain.
It also complicates dating. A disc can be dated by its manufacture, which tells you when the bronze was cast in China, and that says nothing about when it was fitted to a coat in the Baikal region or in Manchuria. Collections catalogued on the mirror's date alone will read older than the practice they document, and that has caused confusion in the literature more than once.