Shen Wei's promise

[china_shop]

At the very end of episode 4, the Envoy meets with Chu Shuzhi to debrief about the face-stealer case. There's a flashback to Ye Olde Haixing Era, and then in present day Shen Wei thinks:

(Revised subs) Once a promise is made, even mountains must move. I promised you, for the sake of the people, for the sake of peace on Haixing, even if it is an endless struggle apart, I will go on.{I will advance.}

(Orig subs) Once a promise is made, even mountains can't get in our way. What I've promised you, for the sake of the people, for the sake of Haixing's peace, even if I have to shoulder burdens whilst moving backward, I will advance forward.

(foxghost on tumblr)
A vow is set in stone
Ten thousand mountains can’t stand in my way
I made you a promise
Even if my burden is heavy and I walk an eternity alone
I would never go back on our agreement


That last one omits "为了天下苍生，为了海星和平", which is the "for the whole world, for the peace of Haixing" part. Taking that line into account, anyone have a theory/speculation about what promise Shen Wei is referring to here?

(Thanks to trobadora for the Foxghost link.)