Here is another one of the many verses in the Doctrine and Covenants which proclaims that the Lamanites are in the area where the church was being built up. They are in New York at this time. It was originally written in September of 1830 but not published until 5 years later.
Doctrine and Covenants 30:
5 Behold, I say unto you, Peter, that you shall take your journey with your brother Oliver; for the time has come that it is expedient in me that you shall open your mouth to declare my gospel; therefore, fear not, but give heed unto the words and advice of your brother, which he shall give you.
6 And be you afflicted in all his afflictions, ever lifting up your heart unto me in prayer and faith, for his and your deliverance; for I have given unto him power to build up my church among the Lamanites;
Doctrine and Covenants 31:
1 And now concerning my servant Parley P. Pratt, behold, I say unto him that as I live I will that he shall declare my gospel and learn of me, and be meek and lowly of heart.
2 And that which I have appointed unto him is that he shall go with my servants, Oliver Cowdery and Peter Whitmer, Jun., into the wilderness among the Lamanites.