Don't know about them personally, but the hiding of treasures predates the ottoman empire by more than 1,000 years.
Jesus Christ talked about finding hidden treasure, so people were hiding things at that time: “The Kingdom of the heavens is like a treasure, hidden in the field, that a man found and hid; and because of his joy, he goes and sells everything he has and buys that field." --- Matthew 13:44
Then, more than 900 years earlier, King Solomon talked about searching for hidden treasure: "Moreover, if you call out for understanding And raise your voice for discernment; If you keep seeking for it as for silver, And you keep searching for it as for hidden treasures; Then you will understand the fear of Jehovah, And you will find the knowledge of God." --- Proverbs 2:4
So, folks have been hiding treasures and others seeking them for at least 3,000 years. Remember though, that is only how long we know it has been going on.
Long time profession / hobby / adventure for humans ... if you have something of value you want to keep safe, you hide it. Today, many hide it in a bank but back then you found a place to secret it away.
As to what may be hidden, what would persons at that time consider to be valuable enough that they might fear it being stolen? Now you know what you may be looking for.
