Complex sentence: After hearing the word "Toslob", the civil guards kept on repeating the word "Toslob" thinking that the said word was the name of the town, which was later changed to "Oslob".
Split into simpler sentences: After hearing the word "Toslob", the civil guards kept on repeating the word "Toslob" thinking that the said word was the name of the town. This has been the start of the word "Toslob" which was later changed to "Oslob".