The general meaning of "Since the mountains behind me are far away from the river, and thousands of mountains are snowing at dusk, I hope you will cherish it" is: From then on, we are on opposite sides of the sky, with endless mountains and endless water. But even though thousands of mountains are blocking your path, or the sky is approaching dusk and the snow is flying, I am not with you, but I sincerely hope that you can take care of yourself.