Mass Chaos in My Backyard

Ok so I've never lived in town growing up so there may be some unwritten rule that you are allowed as children to roam free and play with other children's toys. And if there is I will live to change this rule. My neighbor and I have our playsets close to each other so that we can chat and play on each others playsets. My nephews, BAB, and I were inocently playing in the brand new kiddy pool(not even near my neighbors play set) and all of a sudden there were about 10 kids in my yard and the neighbor's play set. It was mass chaos! I had kids I didn't even know trying to get in my very small kiddy pool! One kid even exclaimed to me "You don't know me!" I was like "Your right. Why are you in my yard?" OKay so I really didn't say that, but the thought came to mind. Anyway, that girl and her 3 sister's and brother's came from a block down! Where are their parents!?!?!?!?