Srila Prabhupada in a lecture described Maharaj Pariksit as the emperor of the whole world and Hastinapura as its capital. Are there any historical records on those details?
Maha-bharata basically deals with South Asia, extending into modern Myanmar and Thailand on the east, and Pakistan and Afghanistan in the West.
There are references to China, but no direct interactions, other than people coming from there to give tribute to Yudhisthira etc.
Of course, we can’t be sure that the names of countries are the same today as they were then, so a reference, for example, to the kingdom of Kekaya may actually indicate a great area than we think today.
There are no descriptions of anyone crossing the ocean or a great sea, although there are analogies to sea travel. But no one actually does it. We know that thousands of years ago, West India actively traded with the Persian Gulf, and that involved sea travel, but the sailors may have been from the Persian side.
Rome traded with India, but again that may have been Romans coming to India, more than Indians going to Rome.
Even in India, at times the kings of other places were supreme rulers. Thus the Maha-bharata states that several generations before Krishna, King Vasu of Cedi (the area where Uttar Pradesh meets Madhya Pradesh) was the emperor of the world.