Upvote:2
According to this page, Kapilavastu and Lumbini are 16 km apart:
His mother queen Mayadevi, (Mahamaya), gave birth to him while travelling to her paternal home. Resting in Lumbini gardens, 16 Km from the Kapilavastu and emerging from a bath with her face to the east, she leant her right arm on a Sal tree (Shorea robusta), and gave birth to the future Buddha.
According to this page, a horse carriage at walking speed can go at 2 - 4 mph or 3.2 to 6.4 km/h.
At a trot, a horse-drawn carriage will go around 8-10 MPH. At a walk, a horse-drawn carriage will go about 2-4 MPH.
So 16km divided by 3.2 - 6.4 km/h is 2.5 to 5 hours. That too at walking speed. At a trot, it can be in an hour.
So why is that unbelievable?
The website you linked seems to propagate an extremist view or conspiracy theory that the Buddha was born in Sri Lanka. Such extremist views are not consistent with mainstream history and archaeology, and is even banned on Suttacentral forums.