Ezra 8:35
Also the children of those that had been carried away, which were come out of the captivity, offered burnt offerings unto the God of Israel, twelve bullocks for all Israel, ninety and six rams, seventy and seven lambs, twelve he goats for a sin offering: all this was a burnt offering unto the LORD.
The children of those who had been carried away, who came out of the captivity and returned with Ezra, offered burnt offerings to the God of Israel. The offerings were both a sin offering and a token of gratitude and thanksgiving. That gratitude and thanksgiving was for the protection of holy angels over them during the journey.