Help with Tibet coins

I think these are all Tibet. I just can't figure out the dating system on these so I'd appreciate any help with dating and attribution.

 

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This may help some.
http://worldcoingallery.com/countries/Tibet_all.php

 

Thanks. That does help with ID but I still need help with the dates.

 

in order 1 sho , 1 skar 1 sho

 

The last one is smaller than the 1 sho. I wonder if it's 5 skar instead? I think the one with the weird rim in half skar.

 

My identifications are:

Coin 1: Tibet 1 Sho, Krause: Y-21, Date: 15-59 (1925)
Coin 2: Tibet 7.5 Skar, Krause: Y-20, Date: 15-56 (1922)
Coin 3: Tibet 5 Skar, Krause: Y-19, Date: 15-56 (1922)

I have coins similar to Coins 1 and 2 but not Coin 3.

 

Thanks! I'll take your word for the dates as I can't figure these out.