In my country, the only legal way to sell a gold bar is to sell it to the central bank. What are the reasons why some countries hoard gold bars?
The answer from the former Chair of the Federal Reserve is in a word: tradition.
Think of the following. Imagine the world suffers a major disaster. Chaos emerges. Rule of law collapses. The monetary system as we know it is destroyed. We could either go back to barter (and surely some will do). Or we can go back to a hard currency, like those in the past, where money was basically in the form of gold coins (and other metals). Thus, gold is, in that sense, THE SAFEST asset, because it will provide you with purchasing power in the case of a major civilisation collapse (and anything in between that and a mere currency crisis). Every kingdom on earth sought to increase their gold reserves (called mercantilism).
But this begs the question, so why gold and not for instance water (which is way more useful for life)? The answer is built upon several factors. One is that gold depreciates quite slowly (paper money however could be lost in a fire). Second, it is easily storable and hard to steal on masse (unlike water). Third, is highly regarder by the rich and powerful (e.g. kings). But the most important reason is sociological. It's a selfulfilling property of gold. It is regarded by other people as the safest asset and therefore it becomes the safest asset.
Gold happens to be an asset class. More importantly it is priced along with other asset classes, as it cannot be valued. Afterall it doesn't have any cashflow. More of it related to psychological bearing. You can price it relatively to index values, other commodities prices, etc. It is also said that it is a measure of faith in Central Bankers and considered as an hedging tool against expansion and debasement of money.
Reasons to hoard could be more than one: It can be inflation, strategic ~ now this one depends on the perspective of the owner Buy so that it can be sold to liquidate at some future point in time to use for expenditures and other various reasons. I mean one can have various motives to own it as an asset class. In short it can have any of the below reasons: Trading Investing Risk Collateral As countries (I presume Govt) don't ponder much into speculation hence that can be ruled out.
You can further check the money supplies and interest rates of each countries and compares with gold prices along with quantities they happen to own if you have access to data at your end