The largest populated place nearby is the Pine Ridge Indian Reservation across the border in South Dakota ; its residents are largely members of the Oglala Sioux Tribe .
DET ADJ ADJ NOUN ADV AUX DET PROPN PROPN PROPN PROPN ADP DET NOUN ADP PROPN PROPN ; PRON NOUN AUX ADV NOUN ADP DET PROPN PROPN PROPN .