The most common and best-value route links the Masai Mara directly to the Serengeti by light aircraft — a roughly 45-minute-to-one-hour flight that avoids the land border crossing entirely, which is the option we build into the large majority of combined Kenya-Tanzania itineraries. An overland border crossing (via the Isebania/Sirari crossing) is possible and cheaper, but adds a genuinely long travel day — often six-plus hours including border formalities — that eats into game-viewing time, and we generally only recommend it for budget-focused itineraries where the cost saving outweighs the lost day. Nairobi and Arusha (Tanzania's northern-circuit gateway) both have reasonable international flight connections, so many combined itineraries fly into one country and out of the other rather than doubling back, which is more efficient if your airline routing supports it. A well-paced combined trip typically runs 10-14 days to do both countries justice without feeling rushed — shorter than that, and we usually recommend picking one country and going deeper rather than skimming both. Timing matters too: Kenya and Tanzania's best migration windows differ by month (see our migration timing guide), so the order you visit them in should follow the herds, not just geography.