You can also use a regular expression to get the different parts:
using System.Text.RegularExpressions;
const string pattern = @"^(?<number>\d+)\s*(?<country>[^,]+),\s*(?<continent>[^,]+)$";
string test1 = "123 USA, America";
string test2 = "126 South Africa, Africa";
Regex r = new Regex(pattern, RegexOptions.Compiled);
Match m = r.Match(test1);
int number = int.Parse(m.Groups["number"].Value);
string country = m.Groups["country"].Value;
string continent = m.Groups["continent"].Value;
m = r.Match(test2);
number = int.Parse(m.Groups["number"].Value);
country = m.Groups["country"].Value;
continent = m.Groups["continent"].Value;