std::chrono::year::min
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   static constexpr std::chrono::year min() noexcept;  | 
(since C++20) | |
Returns the smallest possible year, that is, std::chrono::year(-32767).
Return value
std::chrono::year(-32767)