There seems to be enough support to attempt a time walk based on decades, so let's come quickly to a conclusion how to set it up.
Key points which need to be nailed down are:
A. Adjudicator
B. Direction
C. Rules for posting
D. Standards for dating
A. Adjudicator
That should be easy, I propose 'echizento' and I hope there in no serious objection (especially from 'echizento' himself). Since this thread could run for some time and 'echizento' might want to have a holiday, I would recommend that he nominates as stand-in another moderator with relevant knowledge ('Sap' comes to mind).
B. Direction
While I personally would favour going from the distant past toward 1600, it seems more practical to start with 1591-1600 and word down.
That would avoid trying to find out what a suitable ancient starting date would be. And it also would perhaps be able to trigger some interest from members who rarely (or never) visit this forum.
C. Rules for posting
Similar rules to
https://goccf.com/t/195589 should apply:
1. You must own the coin
2. You must post a picture of the actual coin you own.
3. The coin can be from any place.
4. The decade must be matched according to dating standards (see D).
5. On decade per day. Once a valid coin has been posted for the decade, the next day (CCF time) will be for the next decade.
6. No jumping forward or backwards, only coins fitting the posting day to be posted.
7. Only one coin per post.
8. Not two post for the same decade by the same poster in sequence (ie at least one valid coin from another poster in between two posts by the same poster for the decade of the day).
Any controversy to be amicably resolved - the adjudicator has the final say.
D. Dating standards
If a poster has several coins fitting into the decade of that day, preference should be given to the coin which most clearly fits in.
Clearly coins which show a specific date or are from a ruler whose total reign fits into one decade are no problems.
Also coins which have been dated by records to such a period are no problem.
What is important is that relevant references are given, for the time of a ruler a Wikipedia link will do, when it comes to dating by records an accepted reference work has to be quoted, eg Sear for Roman coinage.
The question is what do to with coins which have a longer minting period, I do see two reasonable options:
a: use the start of the period
b. use the middle of the period
Personally I would favour option 'b' but am quite happy to get along whichever which way.
This might be suitable for minting periods not (substantially) exceeding 30 years, but what to do with coin from a longer minting period.
Actually the maximum justifiable length of a minting period to be used needs to be determined. Personally I consider the 30 years used in the last paragraph to be possible but would prefer a shorter one.
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Would be very happy if everyone would indicate support for A-C and make some more detailed comments on the dating issue.