I think native North America, outside of Mexico, will be the hardest. You could probably do a Southwest line and extend the Mississippian line to include say the Cherokee or Cree in the modern age. Perhaps a Powhatan and Haudenosaunee in the exploration.
The modern age choices are pretty disparate geographically:
East Coast: Cherokee
Great Plains/Midwest: Lakota, Blackfoot, Crow, Comanche, Cree
Southwest: Navajo, Apache
Pacific Northwest: Haida, Tlingit, Salish
Proposed Southwest line: Zuni, Hopi, Navajo/Apache/Maybe Comanche
Proposed Algonquian line: Mississippians, Shawnee/Powhatan, Cree
Proposed Iroquoian line: Mississippians, Haudenosaunee, Cherokee
Leaders: Chief Powhatan, Chief Si'ahl, Sitting Bull, Quanah Parker
The modern age choices are pretty disparate geographically:
East Coast: Cherokee
Great Plains/Midwest: Lakota, Blackfoot, Crow, Comanche, Cree
Southwest: Navajo, Apache
Pacific Northwest: Haida, Tlingit, Salish
Proposed Southwest line: Zuni, Hopi, Navajo/Apache/Maybe Comanche
Proposed Algonquian line: Mississippians, Shawnee/Powhatan, Cree
Proposed Iroquoian line: Mississippians, Haudenosaunee, Cherokee
Leaders: Chief Powhatan, Chief Si'ahl, Sitting Bull, Quanah Parker