Complex sentence: Prior to 1960 Hellmann's and Best Foods were advertised both in the same advertisement, which pointed out that it is known as Hellmann's in the East and Best Foods in the West.
Split into simpler sentences: Prior to 1960, Hellmann's and Best Foods were advertised both in the same advertisements. The ads pointed out that it is known as Hellmann's in the East, and Best Foods in the West.